The Official Windows Phone 7 Patterns & Practices Guide is now available at the Windows Phone 7 Developer Guide community site on CodePlex. This new guide from patterns & practices will help you design and build applications that target the new Windows Phone 7 platform.
At present it has a new guide from patterns & practice which will help you to design and build applications that target the new Windows Phone 7 platform.
The key themes for these projects are: A Windows Phone 7 client application, A Windows Azure backend for the system.
Microsoft will periodically publish early versions of the deliverable on this site.
You can check them HERE.