Shawn Oster will explain you how to add Silverlight Toolkit Controls to the Visual Studio and Blend Toolbox.
Shawn:
I’ve seen a few questions in the Silverlight.net forums asking how to get the Silverlight Toolkit controls into the toolbox/asset library of Visual Studio 2008 and/or Expression Blend 2. There are a bunch of great posts scattered among the tubes on how to do this but I wanted to explain both Visual Studio 2008 and Blend 2 in one post.