Following the MIX’09 opening, in Las Vegas, we announced and make available Silverlight 3 Beta, a preview of the most powerful platform for creating and delivering Rich Internet Applications (RIAs) and media experiences on the Web. 
We also announced and make available Expression Blend 3 Preview with breakthrough tooling advances for Silverlight 3. New features include SketchFlow, a rapid prototyping capability that makes it easier than ever to communicate design intent to stakeholders and rapidly evolve prototypes into finished applications.

Silverlight Version 3 Beta : www.microsoft.com/silverlight
Expression Blend 3 Preview : www.microsoft.com/expression

J.