Back in December of 2004, I commented in my editorial in the PowerBuilder Developer's Journal (PBDJ) about the advent of Smart Clients and how they would give us the benefits of standard client/server applications and internet applications without the downsides of either.
A couple of months later, in February of 2005, we published an article by Rahul Jain about the use of XMLHTTPRequest to develop more rich client internet applications.
Well, it appears that the XMLHTTPRequest approach is gaining some ground. It and other standard technologies like CSS and DOM, are being used in combination in a methodology called Ajax that is delivering some of the same promises that Smart Clients are supposed to bring. If you've seen Google's mail service (Gmail) or Google Maps, you've seen just what it can do.
Of course, the new beta version of Google Groups is also based on that technology. But I don't think that should reflect poorly on Ajax. It just means that even the best technology can be applied poorly. (As you might infer, I'm not particularly impressed wth the latest version of Google Groups.)