Here is a post in which is explained how to use the Ribbit for Silverlight controls in Microsoft's Expression Blend 3.
Ribbit Developers typically create Silverlight applications in one of two ways. The first way is to use our Ribbit for Silverlight controls by adding them into Visual Studio. We have a tutorial of that here. Another way is to use our Ribbit for Silverlight controls in Microsoft's Expression Blend 3.
You can download Ribbit for Silverlight in the Silverlight section of the Ribbit's Developer Center. You must register to be a Ribbit Developer, but registration is free and easy.