It's been a really good day for rich internet applications. Microsoft released Tafiti, which in Swahili means "do research" as a showcase to mix a richer web experience with search (here is Mary Jo's take). I'm actually a fan of these types of things and Tafiti does it better than most. I realize that almost everyone thinks a single text box with a button on a white background is as good as it gets, but I like seeing the out of the box thinking with rich internet applications and something with as much potential as search. I was a fan of Ms. Dewey and think Tafiti has some good concepts.
I like the interface for both switching between search mediums (books, web, feeds, etc) as well as saving searches. There are some good transitions without a lot of bloat. The tree view was also really interesting and being able to merge searches into one then displaying them on the tree seems like it has some potential.
I think the integration with Live shows where Microsoft has a lot of opportunity. They've got a ton of services out there and building Silverlight front ends for them could do a lot to enhance the user experience. The diversity of the Live platform gives them a lot of room to experiment and test what works best for RIAs and their current application suite.