Index: src/ajax.js
===================================================================
--- src/ajax.js	(revision 5914)
+++ src/ajax.js	(working copy)
@@ -76,7 +76,7 @@
 		.map(function(i, elem){
 			var val = jQuery(this).val();
 			return val == null ? null :
-				val.constructor == Array ?
+				jQuery.isArray(val) ?
 					jQuery.map( val, function(val, i){
 						return {name: elem.name, value: val};
 					}) :
@@ -504,7 +504,7 @@
 
 		// If an array was passed in, assume that it is an array
 		// of form elements
-		if ( a.constructor == Array || a.jquery )
+		if ( jQuery.isArray(a) || a.jquery )
 			// Serialize the form elements
 			jQuery.each( a, function(){
 				add( this.name, this.value );
@@ -515,7 +515,7 @@
 			// Serialize the key/values
 			for ( var j in a )
 				// If the value is an array then the key names need to be repeated
-				if ( a[j] && a[j].constructor == Array )
+				if ( jQuery.isArray(a[j]) )
 					jQuery.each( a[j], function(){
 						add( j, this );
 					});
Index: src/core.js
===================================================================
--- src/core.js	(revision 5916)
+++ src/core.js	(working copy)
@@ -407,7 +407,7 @@
 			if ( this.nodeType != 1 )
 				return;
 
-			if ( value.constructor == Array && /radio|checkbox/.test( this.type ) )
+			if ( jQuery.isArray(value) && /radio|checkbox/.test( this.type ) )
 				this.checked = (jQuery.inArray(this.value, value) >= 0 ||
 					jQuery.inArray(this.name, value) >= 0);
 
@@ -621,6 +621,10 @@
 	isFunction: function( fn ) {
 		return !!fn && !!fn.hasOwnProperty && fn instanceof Function;
 	},
+	
+	isArray: function( arr ){
+		return !!arr && arr.constructor == Array;
+	},
 
 	// check if an element is in a (or is an) XML document
 	isXMLDoc: function( elem ) {
Index: src/fx.js
===================================================================
--- src/fx.js	(revision 5914)
+++ src/fx.js	(working copy)
@@ -112,7 +112,7 @@
 	},
 
 	queue: function(type, fn){
-		if ( jQuery.isFunction(type) || ( type && type.constructor == Array )) {
+		if ( jQuery.isFunction(type) || jQuery.isArray(type) ) {
 			fn = type;
 			type = "fx";
 		}
@@ -121,7 +121,7 @@
 			return queue( this[0], type );
 
 		return this.each(function(){
-			if ( fn.constructor == Array )
+			if ( jQuery.isArray(fn) )
 				queue(this, type, fn);
 			else {
 				queue(this, type).push( fn );