If you are interested in creating physics based Games for Windows Phone 7, you might find this useful:
Creating an Air Hockey Game for Windows Phone 7
I created this tutorial for the Expression Toolbox Site, using the Physics Helper Library and the Farseer Physics Engine. The design assets for the game were created by Pixel Lab. The tutorial consists of several videos and source download which walk you through creating this fun physics game!
There are also some other great Windows Phone 7 Tutorials available on the .toolbox site:
Calculator and Daily Awesome show you some of the design-side of Expression Blend. And Golf Tracker shows you how to creatively display and handle data.