Google recently announced that they are supporting a pubsub model for sharing information between gadgets (their name for widgets). I think this is a very good thing in that it is a step toward building more composite functionality on a page by having multiple specialized widgets share information for a greater purpose. Think of it as mashups for widgets (mash-ets?, widg-ups?).
For whatever reason, the developers of the Java Portlet specification never seemed to catch on to the power of inter-widget communication.