Tafiti was very successful and today, Microsoft is announcing the release of the Tafiti Search Visualization source code to CodePlex which means any developer can download, modify, and use the code royalty free (see MS-PL License for all the details).
Tafiti has been released as a Windows Live Quick Application via CodePlex, which is a set of demos developers can download and use as reference implementations or starter kits for the Windows Live Platform. Microsoft hopes developers will enhance the Windows Live Quick Apps via the CodePlex community development platform.
You can see Tafiti running at http://tafiti.mslivelabs.com (or see the original with the Halo3 skin) and to understand how to use it read the walkthrough or watch the video (4.5 minutes).
There is a wealth of information in this codebase such as:
Reusable Silverlight Controls
Code which wraps the Live Search SOAP API
Windows Live ID Web Authentication implementation