Microsoft Press is offering the Programming Windows Phone 7 ebook for free. The book is written by the renowned Charles Petzold. Millions of people have learned Windows programming from the author’s bestseller, Programming Windows. Now you can learn how to program for Windows Phone 7 from a book by the same author. The book shows you the basics of writing applications for Windows Phone 7 using the C# programming language with the Silverlight and XNA 2D frameworks.
Here is the direct link for the book in PDF.