Now Visual Studio 2010 developers can build Windows Azure target cloud applications for Windows Phone 7. Just download and install Windows Azure Toolkit for Windows Phone 7.
Installation of Toolkit adds a Visual Studio project templates for Windows Phone 7 and Windows Azure to the Visual Studio. Also installs class libraries for Windows Azure storage and membership services optimized for use on the phone, a sample application, and documentation.
Download from CodePlex:
Check out more details here:
http://watoolkitwp7.codeplex.com/releases/view/61952