If you're interested in implementing custom chrome in your WPF application, check out Joe Castro's new post at the WPF SDK blog. Drawing in the non-client with Glass, extending the Glass frame in IE7, and more cool stuff is possible by burrowing under WPF into the Windows API to access DWM.
Here's the kind of thing Joe's code enables:
Don't you wish your apps could look like that? Now they can, and without a huge amount of coding.
Get it here.