The definitive guide for .NET developers who want to develop Windows 8 apps will be published in December 2012 by O'Reilly.
Blimey! O'Reilly say you can get the book for $29.99 (normally $49.99)! Sign up for the newsletter and I'll send you the discount code.
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If you're having a look at the book in it's pre-release state, you can access the source code here: