There is a phone as a prize for the "best" XNA game and the "best" Silverlight application. The dealine for entries is Feb 12th so get cracking if you want to enter.
More details at http://blogs.msdn.com/b/ukmsdn/archive/2011/01/29/dddhack-competition-at-ddd9.aspx
Are you a Windows Phone developer? If so, you could be getting rewards for the apps you build and the success they achieve by joining Nokia's DVLUP program.