Foundation 42 a company which makes games for the iPhone as well as other platforms, is one of the first companies to get an app working on the Zune HD, they managed to port an existing iPhone game to the Zune HD in just 12 hours.
The game they used to try this out was a word puzzle game called Wordmonger, and by using the Microsoft XNA, they we able to get a full working version of their game on the Zune HD.
Unfortunately the only way to get the game on your Zune HD, is by downloading the developer kit, as Microsoft has locked the Zune to free, first party apps at the moment.
Lets hope Microsoft opens up the platform soon, as this could be great news for Zune HD owners and Microsoft if game developers can transfer existing games to the Zune HD so easily and quickly.
Check out the video below which shows the comparision of the game working on the iPhone and the Zune HD.