My game is out! I spent my first two months at Microsoft developing Sudoku for Zune, and now my game is available with the Zune 3.1 firmware release. Engadget, among other blogs like Gizmodo and MP3 Insider, are carrying the news. Of course, I'm preferential to the Engadget post because they have Sudoku in the title!
At some point in the near(ish) future, I'm planning on writing a post discussing how the solver in the game works.