“Get to know Windows Phone 7, 7 minutes at a time! In this series of short, code-focused videos you’ll learn how to build applications for Microsoft’s revolutionary new mobile platform, Windows Phone 7. Each video is under seven minutes long, so you can learn something new over your next coffee break!”

http://tinyurl.com/WP7in7

I think these are worth checking out.  I’ve only watched the last one on XNA.  I thought it was well done.