9/15/08 Update: The Microsoft unit test framework now has its own MSDN Code Gallery site, where you'll find the latest framework releases and other information. http://code.msdn.microsoft.com/silverlightut/ If you're looking for the latest Silverlight unit test framework download, look no further: I've packaged up the binaries and am making them available as a .Zip file download attached to this blog post. These are the same exact binaries that we shipped at the MIX conference for Beta 1 - there's very little that changed for unit testing since Beta 1.  Just a few days ago I posted the workaround steps and also updated Visual Studio 2008 test templates for Silverlight 2 Beta 2. I had a great time meeting with customers at a recent "Ask the Experts" event in Redmond, thanks to everyone that attended, I received some great feedback on what people are looking forward to in the Silverlight testing space and will see what I can make happen!

Download the test framework

Download Microsoft.Silverlight.Testing.zip (160kb) Installation instructions included in the Zip

Download the optional templates for Visual Studio

Details here

Unit test framework tutorial

My original walkthrough post will get you up and running in no time.  Also, ScottGu's original post about the test framework. Hope this helps.