I've only shown a few of the features supported with Expression Blend.  All of these features work for both Silverlight and WPF projects.  All of them will also ship in the upcoming Expression Blend 2.5 March preview - which will be available to download (for free) shortly. 

I think you'll find that Visual Studio 2008 and Expression Studio bring a tremendous amount of productivity and power for building great RIA solutions.  Developers and designers can use them together when working on the same projects (and avoid accidentally stepping on each other).  You can also easily have both open together on one machine and edit a single application with them at the same time.

I'll be blogging more about Expression Blend (and a bunch of features in it that I haven't covered yet) once it is available for download.  I'll also post the above simple chat example for download once Silverlight 2 Beta1 ships so that you can open and run the code yourself.

Hope this helps,

Scott