oh, well does that mean if we can get one of the developers for an xna 360 game to release the code we can easily convert the game to work for the zune?
You'd also have to convert the screen size, maybe by using #if ZUNE commands. The zune processor still may not be able to handle it, though. The XBOX has far more processing power than the zune.
A lot of XNA games for the Xbox use a number of more sophisticated APIs not available on the Zune. For example, XNA on the Xbox includes 3D, geometric primitives, shaders, and a lot more. Pretty much all XNA can do on the Zune is stick sprites and text on the screen. :/
However, certain games can indeed be converted. As has already been said, one of the major hurdles is adapting to the Zune's screen resolution (320x240) and input capabilities (2 buttons and a D-pad) from the Xbox's screen resolution (often 720p HD and up) and input capabilities (a controller with a ton of buttons, 2 analog sticks, and rumble).