Since MIX 10, Windows Phone 7 Series have been attracting everyone and if you code apps for Windows Phone or willing to do the same for the new sensation ‘Windows Phone 7 Series’.
Microsoft is offering a free pre-release document or guide, that may help you to design next generation apps for Windows Phones. This guide has 69 pages of prescriptive guidance on how to design great Windows Phone applications.
It’s a preview of the final documentation, so expect tweaks over time, and you can give feedback to Microsoft by sending mail to firstname.lastname@example.org.
The Windows Phone 7 Series UI Design and Interaction Guide is available for download as a PDF and can be grabbed from here.