Edward Jezierski just announced on his blog that the Composite UI Application Block has released.  I've blogged about the CAB before so I won't go into detail about what it is, but if you're building Smart Client applications, you definitely want to check this block out.  The MSDN url for CAB is http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnpag2/html/cab.asp