diff --git a/Foundation/CPArray_KVO.j b/Foundation/CPArray_KVO.j
new file mode 100644
index 000000000..5386f427d
--- /dev/null
+++ b/Foundation/CPArray_KVO.j
@@ -0,0 +1,439 @@
+/*
+ * CPArray+KVO.j
+ * Foundation
+ *
+ * Created by Ross Boucher.
+ * Copyright 2008, 280 North, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+@import "CPArray.j"
+
+@implementation CPObject (CPArrayKVO)
+
+- (id)mutableArrayValueForKey:(id)aKey
+{
+	return [[_CPKVCArray alloc] initWithKey:aKey forProxyObject:self];
+}
+
+- (id)mutableArrayValueForKeyPath:(id)aKeyPath
+{
+    var dotIndex = aKeyPath.indexOf(".");
+    
+    if (dotIndex < 0)
+        return [self mutableArrayValueForKey:aKeyPath];
+
+    var firstPart = aKeyPath.substring(0, dotIndex),
+        lastPart = aKeyPath.substring(dotIndex+1);
+
+    return [[self valueForKeyPath:firstPart] valueForKeyPath:lastPart];
+}
+
+@end
+
+@implementation _CPKVCArray : CPArray
+{
+    id _proxyObject;
+    id _key;
+    
+    SEL         _insertSEL;
+    Function    _insert;
+    
+    SEL         _removeSEL;
+    Function    _remove;
+    
+    SEL         _replaceSEL;
+    Function    _replace;
+    
+    SEL         _objectAtIndexSEL;
+    Function    _objectAtIndex;
+    
+    SEL         _countSEL;
+    Function    _count;
+    
+    SEL         _accessSEL;
+    Function    _access;
+    
+    SEL         _setSEL;
+    Function    _set;
+}
+
++ (id)alloc
+{
+    var a = [];
+    a.isa = self;
+    
+    var ivars = class_copyIvarList(self),
+        count = ivars.length;
+
+    while (count--)
+        a[ivar_getName(ivars[count])] = nil;
+
+    return a;
+}
+
+-(id)initWithKey:(id)aKey forProxyObject:(id)anObject
+{
+    self = [super init];
+
+    _key = aKey;
+    _proxyObject = anObject;
+    
+    var capitalizedKey = _key.charAt(0).toUpperCase() + _key.substring(1);
+    
+    _insertSEL = sel_getName(@"insertObject:in"+capitalizedKey+"AtIndex:");
+    if ([_proxyObject respondsToSelector:selector])
+        _insert = [_proxyObject methodForSelector:selector];
+
+    _removeSEL = sel_getName(@"removeObjectFrom"+capitalizedKey+"AtIndex:");
+    if ([_proxyObject respondsToSelector:selector])
+        _remove = [_proxyObject methodForSelector:selector];
+        
+    _replaceSEL = sel_getName(@"replaceObjectFrom"+capitalizedKey+"AtIndex:withObject:");
+    if ([_proxyObject respondsToSelector:selector])
+        _replace = [_proxyObject methodForSelector:selector];
+        
+    _objectAtIndexSEL = sel_getName(@"objectIn"+capitalizedKey+"AtIndex:");
+    if ([_proxyObject respondsToSelector:selector])
+        _objectAtIndex = [_proxyObject methodForSelector:selector];
+
+    _countSEL = sel_getName(@"countOf"+capitalizedKey);
+    if ([_proxyObject respondsToSelector:selector])
+        _count = [_proxyObject methodForSelector:selector];
+
+    _accessSEL = sel_getName(_key);
+    if ([_proxyObject respondsToSelector:selector])
+        _access = [_proxyObject methodForSelector:selector];
+
+    _setSEL = sel_getName(@"set"+capitalizedKey+":");
+    if ([_proxyObject respondsToSelector:selector])
+        _set = [_proxyObject methodForSelector:selector];
+
+    return self;
+}
+
+- (id)copy
+{
+    var theCopy = [],
+        count = [self count];
+
+    for (var i=0; i<count; i++)
+        [theCopy addObject:[self objectAtIndex:i]];
+
+    return theCopy;
+}
+
+-(id)_representedObject
+{
+    if (_access)
+        return _access(_proxyObject, _accessSEL);
+
+    return [_proxyObject valueForKey:_key];
+}
+
+-(void)_setRepresentedObject:(id)anObject
+{
+    if (_set)
+        return _set(_proxyObject, _setSEL, anObject);
+
+    [_proxyObject setValue:anObject forKey:_key];
+}
+
+- (unsigned)count
+{
+    if (_count)
+        return _count(_proxyObject, _countSEL);
+
+    return [[self _representedObject] count];
+}
+
+- (id)objectAtIndex:(unsigned)anIndex
+{
+    if(_objectAtIndex)
+        return _objectAtIndex(_proxyObject, _objectAtIndexSEL, anIndex);
+
+    return [[self _representedObject] objectAtIndex:anIndex];
+}
+
+- (void)addObject:(id)anObject
+{
+    if (_insert)
+        return _insert(_proxyObject, _insertSEL, anObject, [self count]);
+
+    var target = [[self _representedObject] copy];
+    
+    [target addObject:anObject];
+    [_self _setRepresentedObject:target];
+}
+
+- (void)insertObject:(id)anObject atIndex:(unsigned)anIndex
+{
+    if (_insert)
+        return _insert(_proxyObject, _insertSEL, anObject, anIndex);
+
+    var target = [[self _representedObject] copy];
+    
+    [target insertObject:anObject atIndex:anIndex];
+    [_self _setRepresentedObject:target];
+}
+
+- (void)removeLastObject
+{
+    if(_remove)
+        return _remove(_proxyObject, _removeSEL, [self count]-1); 
+
+    var target = [[self _representedObject] copy];
+    
+    [target removeLastObject];
+    [_self _setRepresentedObject:target];
+}
+
+- (void)removeObjectAtIndex:(unsigned)anIndex
+{
+    if(_remove)
+        return _remove(_proxyObject, _removeSEL, anIndex); 
+
+    var target = [[self _representedObject] copy];
+    
+    [target removeObjectAtIndex:anIndex];
+    [_self _setRepresentedObject:target];
+}
+
+- (void)replaceObjectAtIndex:(unsigned)anIndex withObject:(id)anObject
+{
+    if(_replace)
+        return _replace(_proxyObject, _replaceSEL, anIndex, anObject);
+
+    var target = [[self _representedObject] copy];
+    
+    [target replaceObjectAtIndex:anIndex withObject:anObject];
+    [_self _setRepresentedObject:target];
+}
+
+- (CPArray)objectsAtIndexes:(CPIndexSet)indexes
+{
+    var index = [indexes firstIndex],
+        objects = [];
+
+    while(index != CPNotFound)
+    { 
+        [objects addObject:[self objectAtIndex:index]];
+        index = [indexes indexGreaterThanIndex:index];
+    }
+    
+    return objects;
+}
+
+@end
+
+
+//KVC on CPArray objects act on each item of the array, rather than on the array itself
+
+@implementation CPArray (KeyValueCoding)
+
+- (id)valueForKey:(CPString)aKey
+{
+
+    if (aKey.indexOf("@") === 0)
+    {
+        if (aKey.indexOf(".") !== -1)
+            [CPException raise:CPInvalidArgumentException reason:"called valueForKey: on an array with a complex key ("+aKey+"). use valueForKeyPath:"];
+
+        if (aKey == "@count")
+            return length;
+            
+        return nil;
+    }
+    else
+    {
+        var newArray = [],
+            enumerator = [self objectEnumerator],
+            object;
+            
+        while (object = [enumerator nextObject])
+        {
+            var value = [object valueForKey:aKey];
+            
+            if (!value && value !== "")
+                value = [NSNull null];
+                
+            newArray.push(value);
+        }
+        
+        return newArray;
+    }
+}
+
+- (id)valueForKeyPath:(CPString)aKeyPath
+{
+    if (aKey.indexOf("@") === 0)
+    {            
+        var dotIndex = akey.indexOf("."),
+            operator = aKey.substring(1, dotIndex),
+            parameter = aKey.substring(dotIndex+1);
+        
+        if (kvoOperators[operator])
+            return kvoOperators[operator](self, _cmd, parameter);
+            
+        return nil;
+    }
+    else
+    {
+        var newArray = [],
+            enumerator = [self objectEnumerator],
+            object;
+            
+        while (object = [enumerator nextObject])
+        {
+            var value = [object valueForKeyPath:aKeyPath];
+            
+            if (!value && value !== "")
+                value = [NSNull null];
+                
+            newArray.push(value);
+        }
+        
+        return newArray;
+    }
+}
+
+- (void)setValue:(id)aValue forKey:(CPString)aKey
+{
+    var enumerator = [self objectEnumerator],
+        object;
+    
+    while (object = [enumerator nextObject])
+        [object setValue:aValue forKey:aKey];
+}
+
+- (void)setValue:(id)aValue forKeyPath:(CPString)aKeyPath
+{
+    var enumerator = [self objectEnumerator],
+        object;
+    
+    while (object = [enumerator nextObject])
+        [object setValue:aValue forKeyPath:aKeyPath];
+}
+
+
+@end
+
+var kvoOperators = [];
+
+kvoOperators["avg"] = function avgOperator(self, _cmd, param)
+{
+    var objects = [self valueForKeyPath:param],
+        length = [objects count],
+        average = 0.0;
+
+    while(length--)
+        average += [objects[length] doubleValue] / count;
+
+    return average;
+}
+
+kvoOperators["max"] = function maxOperator(self, _cmd, param)
+{
+    var objects = [self valueForKeyPath:param],
+        length = [objects count] - 1,
+        max = [objects lastObject];
+
+    while (length--)
+    {
+        var item = objects[length];
+        if ([max compare:item] < 0)
+            max = item;
+    }
+
+    return max;
+}
+
+kvoOperators["min"] = function minOperator(self, _cmd, param)
+{
+    var objects = [self valueForKeyPath:param],
+        length = [objects count] - 1,
+        min = [objects lastObject];
+
+    while (length--)
+    {
+        var item = objects[length];
+        if ([min compare:item] > 0)
+            min = item;
+    }
+
+    return min;
+}
+
+kvoOperators["count"] = function countOperator(self, _cmd, param)
+{
+    return [self count];
+}
+
+kvoOperators["sum"] = function sumOperator(self, _cmd, param)
+{
+    var objects = [self valueForKeyPath:param],
+        length = [objects count],
+        sum = 0.0;
+
+    while(length--)
+        sum += [objects[length] doubleValue];
+
+    return sum;
+}
+
+@implementation CPArray (KeyValueObserving)
+
+- (void)addObserver:(id)anObserver toObjectsAtIndexes:(CPIndexSet)indexes forKeyPath:(CPString)aKeyPath options:(unsigned)options context:(id)context
+{
+    var index = [indexes firstIndex];
+    
+    while (index >= 0)
+    {
+        [self[index] addObserver:anObserver forKeyPath:aKeyPath options:options context:context];
+
+        index = [indexes indexGreaterThanIndex:index];
+    }
+}
+
+- (void)removeObserver:(id)anObserver fromObjectsAtIndexes:(CPIndexSet)indexes forKeyPath:(CPString)aKeyPath
+{
+    var index = [indexes firstIndex];
+    
+    while (index >= 0)
+    {
+        [self[index] removeObserver:anObserver forKeyPath:aKeyPath];
+
+        index = [indexes indexGreaterThanIndex:index];
+    }
+}
+
+-(void)addObserver:(id)observer forKeyPath:(CPString)aKeyPath options:(unsigned)options context:(id)context
+{
+    if ([isa instanceMethodForSelector:_cmd]==[NSArray instanceMethodForSelector:_cmd])
+        [CPException raise:CPInvalidArgumentException reason:"Unsupported method on CPArray"];
+    else
+        [super addObserver:observer forKeyPath:aKeyPath options:options context:context];
+}
+
+-(void)removeObserver:(id)observer forKeyPath:(CPString)aKeyPath
+{
+    if ([isa instanceMethodForSelector:_cmd]==[NSArray instanceMethodForSelector:_cmd])
+        [CPException raise:CPInvalidArgumentException reason:"Unsupported method on CPArray"];
+    else
+        [super removeObserver:observer forKeyPath:aKeyPath];
+}
+
+@end
diff --git a/Foundation/CPKeyValueCoding.j b/Foundation/CPKeyValueCoding.j
index 9fccd8845..6a74cfb3f 100644
--- a/Foundation/CPKeyValueCoding.j
+++ b/Foundation/CPKeyValueCoding.j
@@ -278,81 +278,4 @@ CPUnknownUserInfoKey        = @"CPUnknownUserInfoKey";
 
 @end
 
-//KVC on CPArray objects act on each item of the array, rather than on the array itself
-
-@implementation CPArray (KeyValueCoding)
-
-- (id)valueForKey:(CPString)aKey
-{
-    if (aKey.indexOf("@") == 0)
-    {
-        if (aKey == "@count")
-            return length;
-            
-        return nil;
-    }
-    else
-    {
-        var newArray = [],
-            enumerator = [self objectEnumerator],
-            object;
-            
-        while (object = [enumerator nextObject])
-        {
-            var value = [object valueForKey:aKey];
-            
-            if (!value && value !== "")
-                value = [NSNull null];
-                
-            newArray.push(value);
-        }
-        
-        return newArray;
-    }
-}
-
-- (id)valueForKeyPath:(CPString)aKeyPath
-{
-    if (aKey.indexOf("@") == 0)
-    {            
-        return nil;
-    }
-    else
-    {
-        var newArray = [],
-            enumerator = [self objectEnumerator],
-            object;
-            
-        while (object = [enumerator nextObject])
-        {
-            var value = [object valueForKeyPath:aKeyPath];
-            
-            if (!value && value !== "")
-                value = [NSNull null];
-                
-            newArray.push(value);
-        }
-        
-        return newArray;
-    }
-}
-
-- (void)setValue:(id)aValue forKey:(CPString)aKey
-{
-    var enumerator = [self objectEnumerator],
-        object;
-    
-    while (object = [enumerator nextObject])
-        [object setValue:aValue forKey:aKey];
-}
-
-- (void)setValue:(id)aValue forKeyPath:(CPString)aKeyPath
-{
-    var enumerator = [self objectEnumerator],
-        object;
-    
-    while (object = [enumerator nextObject])
-        [object setValue:aValue forKeyPath:aKeyPath];
-}
-
-@end
+@import "CPArray_KVO.j"
diff --git a/Foundation/CPKeyValueObserving.j b/Foundation/CPKeyValueObserving.j
index 4e6fc1cdd..e40cb50e3 100644
--- a/Foundation/CPKeyValueObserving.j
+++ b/Foundation/CPKeyValueObserving.j
@@ -31,12 +31,18 @@
 
 - (void)willChangeValueForKey:(CPString)aKey
 {
-
 }
 
 - (void)didChangeValueForKey:(CPString)aKey
 {
+}
 
+- (void)willChange:(CPKeyValueChange)change valuesAtIndexes:(CPIndexSet)indexes forKey:(CPString)key
+{
+}
+
+- (void)didChange:(CPKeyValueChange)change valuesAtIndexes:(CPIndexSet)indexes forKey:(CPString)key
+{
 }
 
 - (void)addObserver:(id)anObserver forKeyPath:(CPString)aPath options:(unsigned)options context:(id)aContext
@@ -79,9 +85,6 @@ CPKeyValueObservingOptionOld        = 1 << 1;
 CPKeyValueObservingOptionInitial    = 1 << 2;
 CPKeyValueObservingOptionPrior      = 1 << 3;
 
-//convenience
-var kvoNewAndOld = CPKeyValueObservingOptionNew|CPKeyValueObservingOptionOld;
-
 // KVO Change Dictionary Keys
 CPKeyValueChangeKindKey                 = @"CPKeyValueChangeKindKey";
 CPKeyValueChangeNewKey                  = @"CPKeyValueChangeNewKey";
@@ -89,6 +92,15 @@ CPKeyValueChangeOldKey                  = @"CPKeyValueChangeOldKey";
 CPKeyValueChangeIndexesKey              = @"CPKeyValueChangeIndexesKey";
 CPKeyValueChangeNotificationIsPriorKey  = @"CPKeyValueChangeNotificationIsPriorKey";
 
+// KVO Change Types
+CPKeyValueChangeSetting     = 1;
+CPKeyValueChangeInsertion   = 2;
+CPKeyValueChangeRemoval     = 3;
+CPKeyValueChangeReplacement = 4;
+
+//convenience
+var kvoNewAndOld = CPKeyValueObservingOptionNew|CPKeyValueObservingOptionOld;
+
 // Map of real objects to their KVO proxy
 var KVOProxyMap = [CPDictionary dictionary],
     DependentKeysMap = [CPDictionary dictionary];
@@ -173,22 +185,23 @@ var KVOProxyMap = [CPDictionary dictionary],
         capitalizedKey = aKey.charAt(0).toUpperCase() + aKey.substring(1),
         found = false,
         replacementMethods = [
-            "set"+capitalizedKey+":",
-            "_set"+capitalizedKey+":",
-            "insertObject:in"+capitalizedKey+"AtIndex:",
-            "replaceObjectIn"+capitalizedKey+"AtIndex:",
-            "removeObjectFrom"+capitalizedKey+"AtIndex:"        
+            "set"+capitalizedKey+":", _kvoMethodForMethod,
+            "_set"+capitalizedKey+":", _kvoMethodForMethod,
+            "insertObject:in"+capitalizedKey+"AtIndex:", _kvoInsertMethodForMethod,
+            "replaceObjectIn"+capitalizedKey+"AtIndex:withObject:", _kvoReplaceMethodForMethod,
+            "removeObjectFrom"+capitalizedKey+"AtIndex:", _kvoRemoveMethodForMethod
         ];
     
-    for (var i=0, count=replacementMethods.length; i<count; i++)
+    for (var i=0, count=replacementMethods.length; i<count; i+=2)
     {
-        var theSelector = sel_getName(replacementMethods[i]);
+        var theSelector = sel_getName(replacementMethods[i]),
+            theReplacementMethod = replacementMethods[i+1];
 
         if ([_nativeClass instancesRespondToSelector:theSelector])
         {
             var theMethod = class_getInstanceMethod(_nativeClass, theSelector);
 
-            class_addMethod(_targetObject.isa, theSelector, _kvoMethodForMethod(aKey, theMethod), "");
+            class_addMethod(_targetObject.isa, theSelector, theReplacementMethod(aKey, theMethod), "");
 
             found = true;
         }
@@ -282,21 +295,41 @@ var KVOProxyMap = [CPDictionary dictionary],
     }
 }
 
-- (void)_sendNotificationsForKey:(CPString)aKey isBefore:(BOOL)isBefore
+//FIXME: We do not compute and cache if CPKeyValueObservingOptionOld is needed, so we may do unnecessary work
+
+- (void)_sendNotificationsForKey:(CPString)aKey changeOptions:(CPDictionary)changeOptions isBefore:(BOOL)isBefore
 {
     var changes = [_changesForKey objectForKey:aKey];
 
     if (isBefore)
     {
-        changes = [CPDictionary dictionary];
+        changes = changeOptions;
 
-        var oldValue = [_targetObject valueForKey:aKey];
-
-        if (!oldValue && oldValue !== "")
-            oldValue = [CPNull null];
+        var indexes = [changes objectForKey:CPKeyValueChangeIndexesKey];
+        
+        if (indexes)
+        {
+            var type = [changes objectForKey:CPKeyValueChangeKindKey];
+            
+            // for to-many relationships, oldvalue is only sensible for replace and remove
+            if (type == CPKeyValueChangeReplacement || type == CPKeyValueChangeRemoval)
+            {
+                //FIXME: do we need to go through and replace "" with CPNull? 
+                var oldValues = [[_targetObject mutableArrayValueForKeyPath:aKey] objectsAtIndexes:indexes];
+                [changes setValue:oldValues forKey:CPKeyValueChangeOldKey];
+            }
+        }
+        else
+        {
+            var oldValue = [_targetObject valueForKey:aKey];
+    
+            if (!oldValue && oldValue !== "")
+                oldValue = [CPNull null];
 
+            [changes setObject:oldValue forKey:CPKeyValueChangeOldKey];
+        }
+        
         [changes setObject:1 forKey:CPKeyValueChangeNotificationIsPriorKey];
-        [changes setObject:oldValue forKey:CPKeyValueChangeOldKey];
 
         [_changesForKey setObject:changes forKey:aKey];
     }
@@ -304,12 +337,29 @@ var KVOProxyMap = [CPDictionary dictionary],
     {
         [changes removeObjectForKey:CPKeyValueChangeNotificationIsPriorKey];
 
-        var newValue = [_targetObject valueForKey:aKey];
-
-        if (!newValue && newValue !== "")
-            newValue = [CPNull null];
-
-        [changes setObject:newValue forKey:CPKeyValueChangeNewKey];
+        var indexes = [changes objectForKey:CPKeyValueChangeIndexesKey];
+        
+        if (indexes)
+        {
+            var type = [changes objectForKey:CPKeyValueChangeKindKey];
+            
+            // for to-many relationships, oldvalue is only sensible for replace and remove
+            if (type == CPKeyValueChangeReplacement || type == CPKeyValueChangeInsertion)
+            {
+                //FIXME: do we need to go through and replace "" with CPNull? 
+                var oldValues = [[_targetObject mutableArrayValueForKeyPath:aKey] objectsAtIndexes:indexes];
+                [changes setValue:oldValues forKey:CPKeyValueChangeNewKey];
+            }
+        }
+        else
+        {
+            var newValue = [_targetObject valueForKey:aKey];
+    
+            if (!newValue && newValue !== "")
+                newValue = [CPNull null];
+    
+            [changes setObject:newValue forKey:CPKeyValueChangeNewKey];
+        }
     }
     
     var observers = [[_observersForKey objectForKey:aKey] allValues],
@@ -331,7 +381,7 @@ var KVOProxyMap = [CPDictionary dictionary],
         return;
 
     for (var i=0, count=keysComposedOfKey.length; i<count; i++)
-        [self _sendNotificationsForKey:keysComposedOfKey[i] isBefore:isBefore];
+        [self _sendNotificationsForKey:keysComposedOfKey[i] changeOptions:changeOptions isBefore:isBefore];
 }
 
 @end
@@ -345,7 +395,9 @@ var KVOProxyMap = [CPDictionary dictionary],
     if (!aKey)
         return;
 
-    [[_CPKVOProxy proxyForObject:self] _sendNotificationsForKey:aKey isBefore:YES];
+    var changeOptions = [CPDictionary dictionaryWithObject:CPKeyValueChangeSetting forKey:CPKeyValueChangeKindKey];
+
+    [[_CPKVOProxy proxyForObject:self] _sendNotificationsForKey:aKey changeOptions:changeOptions isBefore:YES];
 }
 
 - (void)didChangeValueForKey:(CPString)aKey
@@ -353,7 +405,25 @@ var KVOProxyMap = [CPDictionary dictionary],
     if (!aKey)
         return;
 
-    [[_CPKVOProxy proxyForObject:self] _sendNotificationsForKey:aKey isBefore:NO];
+    [[_CPKVOProxy proxyForObject:self] _sendNotificationsForKey:aKey changeOptions:nil isBefore:NO];
+}
+
+- (void)willChange:(CPKeyValueChange)change valuesAtIndexes:(CPIndexSet)indexes forKey:(CPString)aKey
+{
+    if (!aKey)
+        return;
+
+    var changeOptions = [CPDictionary dictionaryWithObjects:[change, indexes] forKeys:[CPKeyValueChangeKindKey, CPKeyValueChangeIndexesKey]];
+    
+    [[_CPKVOProxy proxyForObject:self] _sendNotificationsForKey:aKey changeOptions:changeOptions isBefore:YES];
+}
+
+- (void)didChange:(CPKeyValueChange)change valuesAtIndexes:(CPIndexSet)indexes forKey:(CPString)aKey
+{
+    if (!aKey)
+        return;
+
+    [[_CPKVOProxy proxyForObject:self] _sendNotificationsForKey:aKey changeOptions:nil isBefore:NO];
 }
 
 - (Class)class
@@ -474,48 +544,42 @@ var _CPKVOInfoMake = function _CPKVOInfoMake(anObserver, theOptions, aContext, a
 
 var _kvoMethodForMethod = function _kvoMethodForMethod(theKey, theMethod)
 {
-    return function(self) 
+    return function(self, _cmd, object) 
     {
         [self willChangeValueForKey:theKey];
-        theMethod.method_imp.apply(self, arguments);
+        theMethod.method_imp(self, _cmd, object);
         [self didChangeValueForKey:theKey];
     }
 }
 
-@implementation CPArray (KeyValueObserving)
-
-- (void)addObserver:(id)anObserver toObjectsAtIndexes:(CPIndexSet)indexes forKeyPath:(CPString)aKeyPath options:(unsigned)options context:(id)context
+var _kvoInsertMethodForMethod = function _kvoInsertMethodForMethod(theKey, theMethod)
 {
-    var index = [indexes firstIndex];
-    
-    while (index >= 0)
+    return function(self, _cmd, object, index)
     {
-        [self[index] addObserver:anObserver forKeyPath:aKeyPath options:options context:context];
-
-		index = [indexes indexGreaterThanIndex:index];
+        [self willChange:CPKeyValueChangeInsertion valuesAtIndexes:[CPIndexSet indexSetWithIndex:index] forKey:theKey];
+        theMethod.method_imp(self, _cmd, object, index);
+        [self didChange:CPKeyValueChangeInsertion valuesAtIndexes:[CPIndexSet indexSetWithIndex:index] forKey:theKey]
     }
 }
 
-- (void)removeObserver:(id)anObserver fromObjectsAtIndexes:(CPIndexSet)indexes forKeyPath:(CPString)aKeyPath
+var _kvoReplaceMethodForMethod = function _kvoReplaceMethodForMethod(theKey, theMethod)
 {
-    var index = [indexes firstIndex];
-    
-    while (index >= 0)
+    return function(self, _cmd, index, object)
     {
-        [self[index] removeObserver:anObserver forKeyPath:aKeyPath];
-
-		index = [indexes indexGreaterThanIndex:index];
+        [self willChange:CPKeyValueChangeReplacement valuesAtIndexes:[CPIndexSet indexSetWithIndex:index] forKey:theKey];
+        theMethod.method_imp(self, _cmd, index, object);
+        [self didChange:CPKeyValueChangeReplacement valuesAtIndexes:[CPIndexSet indexSetWithIndex:index] forKey:theKey]
     }
 }
 
--(void)addObserver:(id)observer forKeyPath:(CPString)aKeyPath options:(unsigned)options context:(id)context
+var _kvoRemoveMethodForMethod = function _kvoRemoveMethodForMethod(theKey, theMethod)
 {
-    [CPException raise:CPInvalidArgumentException reason:"Unsupported method on CPArray"];
+    return function(self, _cmd, index)
+    {
+        [self willChange:CPKeyValueChangeRemoval valuesAtIndexes:[CPIndexSet indexSetWithIndex:index] forKey:theKey];
+        theMethod.method_imp(self, _cmd, index);
+        [self didChange:CPKeyValueChangeRemoval valuesAtIndexes:[CPIndexSet indexSetWithIndex:index] forKey:theKey]
+    }
 }
 
--(void)removeObserver:(id)observer forKeyPath:(CPString)aKeyPath
-{
-    [CPException raise:CPInvalidArgumentException reason:"Unsupported method on CPArray"];
-}
-
-@end
+@import "CPArray_KVO.j"
diff --git a/Tests/Foundation/CPKVOTest.j b/Tests/Foundation/CPKVOTest.j
index b10b986c8..909c01ec5 100644
--- a/Tests/Foundation/CPKVOTest.j
+++ b/Tests/Foundation/CPKVOTest.j
@@ -1,5 +1,5 @@
-import <Foundation/CPKeyValueCoding.j>
-import <Foundation/CPKeyValueObserving.j>
+@import <Foundation/CPKeyValueCoding.j>
+@import <Foundation/CPKeyValueObserving.j>
 
 @implementation CPKVOTest : OJTestCase
 {
@@ -14,6 +14,11 @@ import <Foundation/CPKeyValueObserving.j>
     id      focus;
 }
 
+- (void)setUp
+{
+    _sawObservation = NO;
+}
+
 - (void)testAddObserver
 {
     bob = [[PersonTester alloc] init];
@@ -167,7 +172,7 @@ import <Foundation/CPKeyValueObserving.j>
     
     [cs101 setTeacher:bob];
     
-    [cs101 addObserver:self forKeyPath:@"teacher.name" options:nil context:"testMultipartKey"];
+    [cs101 addObserver:self forKeyPath:@"teacher.name" options:0 context:"testMultipartKey"];
     
     [bob setName:@"bob"];
     
@@ -184,7 +189,7 @@ import <Foundation/CPKeyValueObserving.j>
     [cs101 setTeacher:bob];
     [bob setValue:focus forKey:"car"];
 
-    [cs101 addObserver:self forKeyPath:@"teacher.car.model" options:nil context:"testThreePartKey"];
+    [cs101 addObserver:self forKeyPath:@"teacher.car.model" options:0 context:"testThreePartKey"];
 
     [focus setValue:"ford focus" forKey:"model"];
     [self assertTrue: _sawObservation message:"Never recieved an observation"];
@@ -199,7 +204,7 @@ import <Foundation/CPKeyValueObserving.j>
     [cs101 setTeacher:bob];
     [focus setValue:"2000" forKey:"year"];
 
-    [cs101 addObserver:self forKeyPath:@"teacher.car.year" options:nil context:"testThreePartKeyPart2"];
+    [cs101 addObserver:self forKeyPath:@"teacher.car.year" options:0 context:"testThreePartKeyPart2"];
     
     [bob setValue:focus forKey:"car"];
 
@@ -213,7 +218,7 @@ import <Foundation/CPKeyValueObserving.j>
     
     [cs101 setTeacher:bob];
     
-    [cs101 addObserver:self forKeyPath:@"teacher.name" options:nil context:"testRemoveMultipartKey"];
+    [cs101 addObserver:self forKeyPath:@"teacher.name" options:0 context:"testRemoveMultipartKey"];
     
     [cs101 removeObserver:self forKeyPath:@"teacher.name"];
     
@@ -231,7 +236,7 @@ import <Foundation/CPKeyValueObserving.j>
     [cs101 setTeacher:bob];
     [bob setValue:focus forKey:"car"];
 
-    [cs101 addObserver:self forKeyPath:@"teacher.car.model" options:nil context:"testRemoveThreePartKey"];
+    [cs101 addObserver:self forKeyPath:@"teacher.car.model" options:0 context:"testRemoveThreePartKey"];
     [cs101 removeObserver:self forKeyPath:@"teacher.car.model"];
 
     [focus setValue:"ford focus" forKey:"model"];
@@ -250,7 +255,7 @@ import <Foundation/CPKeyValueObserving.j>
     [a setValue:[E new] forKeyPath:"b.c.d.e"];
     [a setValue:[F new] forKeyPath:"b.c.d.e.f"];
     
-    [a addObserver:self forKeyPath:"b.c.d.e.f" options:nil context:"testCrazyKeyPathChanges"];
+    [a addObserver:self forKeyPath:"b.c.d.e.f" options:0 context:"testCrazyKeyPathChanges"];
     
     [a setValue:[D new] forKeyPath:"b.c.d"];
     
@@ -267,7 +272,7 @@ import <Foundation/CPKeyValueObserving.j>
     [a setValue:[E new] forKeyPath:"b.c.d.e"];
     [a setValue:[F new] forKeyPath:"b.c.d.e.f"];
     
-    [a addObserver:self forKeyPath:"b.c.d.e.f" options:nil context:"testCrazyKeyPathChanges2"];
+    [a addObserver:self forKeyPath:"b.c.d.e.f" options:0 context:"testCrazyKeyPathChanges2"];
     
     [a setValue:nil forKeyPath:"b.c"];
     
@@ -284,13 +289,42 @@ import <Foundation/CPKeyValueObserving.j>
     [a setValue:[E new] forKeyPath:"b.c.d.e"];
     [a setValue:[F new] forKeyPath:"b.c.d.e.f"];
     
-    [a addObserver:self forKeyPath:"b.c.d.e.f" options:nil context:"testCrazyKeyPathChanges3"];
+    [a addObserver:self forKeyPath:"b.c.d.e.f" options:0 context:"testCrazyKeyPathChanges3"];
     
     [a setValue:7 forKeyPath:"b.c.d.e.f"];
     
     [self assertTrue: _sawObservation message:"Never recieved an observation"];
 }
 
+- (void)testInsertIntoToManyProperty
+{
+    var tester = [ToManyTester new];
+    
+    [tester setValue:[1, 2, 3, 4] forKey:@"managedObjects"];
+    
+    
+    [tester addObserver:self forKeyPath:@"managedObjects" options:0 context:"testInsertIntoToManyProperty"];
+    
+    [tester insertObject:5 inManagedObjectsAtIndex:4];
+    
+    [self assertTrue: _sawObservation message:"Never recieved an observation"];
+}
+
+- (void)testRemoveFromToManyProperty
+{
+    var tester = [ToManyTester new];
+    
+    [tester setValue:[1, 2, 3, 4] forKey:@"managedObjects"];
+    
+    [tester addObserver:self forKeyPath:@"managedObjects" options:0 context:"testRemoveFromToManyProperty"];
+    
+    [tester removeObjectFromManagedObjectsAtIndex:0];
+    
+    [self assertTrue: _sawObservation message:"Never recieved an observation"];
+}
+
+
+
 - (void)testPerformance
 {
     bob = [PersonTester new];
@@ -432,6 +466,25 @@ import <Foundation/CPKeyValueObserving.j>
             _sawDependentObservation = YES;
             break;
 
+        case "testInsertIntoToManyProperty":
+            var type = [changes objectForKey:CPKeyValueChangeKindKey];
+            [self assertTrue: type == CPKeyValueChangeInsertion message: "Should have been an insertion, was: "+type];
+            
+            var values = [changes objectForKey:CPKeyValueChangeNewKey];
+            [self assertTrue: [values isEqual:[5]] message: "array should have contained 5, was: "+values+" type: "+[values.isa description]+" length: "+values.length];
+            
+            break;
+
+        case "testRemoveFromToManyProperty":
+            var type = [changes objectForKey:CPKeyValueChangeKindKey];
+            [self assertTrue: type == CPKeyValueChangeRemoval message: "Should have been a removal, was: "+type];
+            
+            var values = [changes objectForKey:CPKeyValueChangeOldKey];
+            [self assertTrue: [values isEqual:[1]] message: "array should have contained 1, was: "+values+" type: "+[values.isa description]+" length: "+values.length];
+            [[anObject valueForKey:@"managedObjects"] isEqual:[2, 3, 4]];
+            
+            break;
+            
         default:
             [self assertFalse:YES message:"unhandled observation, must be an error"];
             return;
@@ -501,6 +554,33 @@ import <Foundation/CPKeyValueObserving.j>
 
 @end
 
+@implementation ToManyTester : CPObject
+{
+    CPArray managedObjects;
+}
+
+- (unsigned int)countOfManagedObjects
+{
+    return [managedObjects count];
+}
+
+- (id)objectInManagedObjectsAtIndex:(unsigned)anIndex
+{
+    return [managedObjects objectAtIndex:anIndex];
+}
+
+- (void)removeObjectFromManagedObjectsAtIndex:(unsigned)anIndex
+{
+    [managedObjects removeObjectAtIndex:anIndex];
+}
+
+- (void)insertObject:(id)anObject inManagedObjectsAtIndex:(unsigned)anIndex
+{
+    [managedObjects insertObject:anObject atIndex:anIndex];
+}
+
+@end
+
 @implementation A : CPObject
 {
     id  b;