As you know Zune uses much of the hardware of the Toshiba Gigabeat S series and is constructed also by Toshiba. The RockBox team has made the first steps, loading the first "Hello World" modified firmware for the "S"...
Of course the question is how useful this can be for Zune. I'm afraid the answer is: not much. The Zune team has thought of this "bug" used in the S series already and has closed this backdoor.
RockBox is an alternative firmware for many music players and normally its developers use hacks to install it on many Digital Players. You can read an older article describing RockBox as a possibility for Zune by our friend from the inside, Ioannis Koutoulakis who also sent the tip about this.
And here are the juicy photos :
You can read more about the Gigabeat S moded firmware you can read more on the RockBox Forum. Congratulations guys!
The v.00000001 bootloader can be downloaded from here:
http://rapidshare.com/files/42253579/gigabeatS.hello-world-rockbox.rar.html
Thanks for the tip Ioannis.