For all you Flash coders out there, Robin Debreuil has just released the Swf2XNA program to leverage your skills into WP7 games. To quote him
Swf2XNA is now live! This is an open source (BSD) program that allows you to make Windows/XBox/Win7 games by leveraging Flash for assets and layout, as well as using Box2D visually. It makes 2D games in XNA quite simple to make!
Check out his blog for more information and happy coding!