Actually, tafiti apparently means "do research" in Swahili. I guess it wouldn't sound as fun if the project was called "do research." I have been playing with the Tafiti interface recently, even for a few days pre-launch. It's very visually cool like almost everything I've seen built on Silverlight. The design element is married tightly with the workings of the interface. It also has some neat functionality like the post-it note stack of search queries that builds up and the ability to drag and drop in order to save off your results on a shelf or folder tab. I also really like being able to rotate between searching RSS, web and news sources. 

Reading through some early blog reviews about the beta product, people seem to dislike the tree view of the search but I think it has merit. It may not be readily useful but it never hurts to see something from multiple angles. It provides an alternate way to visualize search queries and results much like looking at clustering and tag clouds. Another cool example of Silverlight and search is an app written by Criteo who has built a blog search and discovery interface that puts you in the driver's seat of the Star War's Millenium Falcon. 

I do think Tafiti is a lot of overhead for maybe a simple search query but the purpose is not to replace search as we know it. I think Tafiti is asking us to imagine what could be possible.  What the project is for is to demonstrate the power of using Silverlight to take an existing scenario that we are all very familiar with and make it exciting and richer both in a design sense and in an interactive sense.