Make way for SketchFlow, a template which allows you to muster up prototype apps for Windows Phone 7 using SketchFlow features and controls, which are then ran in the SketchFlow player (not the emulator) for quick testing, feedback from clients and more. You can check out the documentation for it over at CodePlex, it's really interesting.

"For the phone template we have added a number of unique phone features to speed up the prototyping process such as pivot and panorama, date and time pickers, map controls, the application bar as well full screen mockups of features such as the camera, Bing search, the app list and home screen."

Please note that you'll need to be using Blend 4 with SketchFlow enabled (this is the version of Blend that comes with both Expression Studio 4 Ultimate and Visual Studio 2010 Ultimate) you also need to have the Mango developer tools for Windows Phone installed.

Source: SketchFlow