I just ran into this.
A new version of Tafiti, the silverlight search engine has been released. Not only that, this time around, the source code is on codeplex.
Tafiti though, is more than just silverlight. It is a good demonstration of the upcoming live platform from Microsoft. For instance, Tafiti integrates WLID (Windows live ID) API and the search API.
Technically, it would be possible to integrate WLID + MOSS Search API instead and build this awesome Silverlight front end. It would be incredible to have a search wheel between different search scopes, and the ability to save my search results.
All of it, of course in a beautiful silverlight front end.
More info on liveside.net and on Angus' blog.