O’Reilly has a special offer on the new book that Charles Petzold is working on, Programming Windows 6th Edition. This should be a great book covering Windows 8 app development in C# and XAML.
You can get this book for $10 now (offer lasts till 31st May), and future editions of this book, as and when new chapters are added, will be available to you for free.
Read more at Charles’ blog here: http://www.charlespetzold.com/blog/2012/05/An-Experiment-in-Book-Publishing.html