$.Callbacks, $.Topic and notify/progress on $.Deferred.

src/topic.js

@@ -0,0 +1,45 @@
+(function( jQuery ) {
+
+	var topics = {},
+		sliceTopic = [].slice;
+
+	jQuery.Topic = function( id ) {
+		var callbacks,
+			method,
+			topic = id && topics[ id ];
+		if ( !topic ) {
+			callbacks = jQuery.Callbacks();
+			topic = {
+				publish: callbacks.fire,
+				subscribe: callbacks.add,
+				unsubscribe: callbacks.remove
+			};
+			if ( id ) {
+				topics[ id ] = topic;
+			}
+		}
+		return topic;
+	};
+
+	jQuery.extend({
+		subscribe: function( id ) {
+			var topic = jQuery.Topic( id ),
+				args = sliceTopic.call( arguments, 1 );
+			topic.subscribe.apply( topic, args );
+			return {
+				topic: topic,
+				args: args
+			};
+		},
+		unsubscribe: function( id ) {
+			var topic = id && id.topic || jQuery.Topic( id );
+			topic.unsubscribe.apply( topic, id && id.args ||
+					sliceTopic.call( arguments, 1 ) );
+		},
+		publish: function( id ) {
+			var topic = jQuery.Topic( id );
+			topic.publish.apply( topic, sliceTopic.call( arguments, 1 ) );
+		}
+	});
+
+})( jQuery );