Here’s a free ebook written by Charles Petzold, one of the famous author on Developing for Windows Phone 7 .
The book is titled “Programming Windows Phone 7” and is from Microsoft Press .
The book contains 24 chapters and about 1000 pages ..
You can download the ebook in the PDF format here .
Kick start the WP7 Development with this useful ebook .
Read more at MSDN Blog here.