Index: core.js
===================================================================
--- core.js	(revision 6308)
+++ core.js	(working copy)
@@ -141,25 +141,45 @@
 
 	// Take an array of elements and push it onto the stack
 	// (returning the new matched element set)
-	pushStack: function( elems, name, selector ) {
-		// Build a new jQuery matched element set
-		var ret = jQuery( elems || null );
-
-		// Add the old object onto the stack (as a reference)
-		ret.prevObject = this;
-
-		ret.context = this.context;
-
-		if ( name === "find" ) {
-			ret.selector = this.selector + (this.selector ? " " : "") + selector;
-		} else if ( name ) {
-			ret.selector = this.selector + "." + name + "(" + selector + ")";
+	pushStack: (function(){
+		var concatChar = {
+			find: "",
+			children: "> ",
+			next: "+ ",
+			siblings: '~ '
+		};
+		function concatSelector(first, last, concatName){
+			return (concatChar[concatName] !== undefined) ? first + (first ? " " : "")+ concatChar[concatName] + last : first + "." + concatName + "(" + last + ")";
 		}
+		
+		function concatMultiSelector( contextSelector, appendSelector, concatName ){
+			contextSelector = contextSelector.split(',');
+			appendSelector = appendSelector.split(',');
+			var ret = [];
+			for(var i = 0; i < contextSelector.length; i++){
+				for(var j = 0; j < appendSelector.length; j++){
+					ret.push( concatSelector( jQuery.trim( contextSelector[i] ), jQuery.trim( appendSelector[j] ), concatName ) );
+				}
+			}	
+			return ret.join(', ');
+		}
+		
+		return function( elems, name, selector ) {
+			// Build a new jQuery matched element set
+			var ret = jQuery( elems || null );
+	
+			// Add the old object onto the stack (as a reference)
+			ret.prevObject = this;
+	
+			ret.context = this.context;
+			
+			ret.selector = (this.selector.indexOf(',') !== -1 || selector.indexOf(',') !== -1) ? concatMultiSelector( this.selector, selector, name ) : concatSelector( this.selector, selector, name );
+			
+			// Return the newly-formed element set
+			return ret;
+		}
+	})(),
 
-		// Return the newly-formed element set
-		return ret;
-	},
-
 	// Force the current matched set of elements to become
 	// the specified array of elements (destroying the stack in the process)
 	// You should use pushStack() in order to do this, but maintain the stack