Andrew Shorten has just created the "Microsoft blog for and about UK Web Agencies".
His first post is about getting started with designing rich User Experiences on the Microsoft platform and technologies like WPF, WPF/E, Expression et. al.
I've been playing around with Expression for the last couple of days and it's been a great experience I have to say. Expression Design, despite being in Beta is solid and is now my tool of choice when it comes to digital image manipulation. More on that soon though...
Check out their blog here - it looks like the Expression UI.