Microsoft's put out XNA extensions for Zune HD, as you can see here.

The update adds the following functionality:

  • The ability to target and develop for the Zune HD media player.
  • The addition of new Touch APIs to the XNA Framework for use on the Zune HD.
  • The addition of new Accelerometer APIs to the XNA Framework for use on the Zune HD.

S**t your pants right now, Apple. Actually, maybe hold off until Microsoft manages to release Zune anywhere else apart from America.

Thanks, Roybott.