I’ve been playing around the Tafiti beta, which uses Microsoft’s Silverlight technology. The system is little more than a proof of concept at the moment, but I must confess, I’m impressed. It offers easy navigation between web, rss, image, news and book seaches, and boasts an interactive tree view (which is pretty much useless but looks fantastic).
Tahiti is my first Silverlight experience, and from first impressions, it seems identical from Flash from a user experience perspective. It remains to be seen whether it’ll prove to be a serious alternative in the long run.