First up, the UI Design and Interaction Guide for Windows Phone 7 v2.0 . Guide provides detailed information about:
- UI elements and controls,
- UI system behaviors
- nteraction model for the touch interface
Designers and developers should read this guide to learn about the dos and don’ts of UI implementations for their Windows Phone apps. There is Windows Phone Developer Tools documentation
Another worth telling resource are Design Templates for Windows Phone 7. These are a collection of 28 layered Photoshop template files and the Segoe WP font family that can be used to create pixel-perfect application layouts, to help guide UI development, or to pitch an idea. On Graffletopia you can find these Windows Phone stencils
Last but not the least App Hub center with getting started guide which provides the tools and resources you need to create, distribute, and merchandise app.
