iRecovery has been modified to send encrypted firmware files to the iPod nano 6G by developer Steven Troughton-Smith.
After some interesting discoveries by James Whelton, Troughton-Smith did some investigating and found what seems to be DFU mode. “Hold down the restart buttons until you get a black screen (it reboots twice) and iTunes sees the device and alerts you.”
After accomplishing this he modified iRecovery to send encrypted firmware files to the iPod which could finally bring about custom apps for the device.
So, basically, it seems we can send encrypted firmware files to the iPod, and have them execute, similar to what is used to jailbreak the iPhone. If the nano rejects the file (i.e. unsigned, invalid), it reboots.
While this by itself isn’t that cool, hopefully the info will inspire someone else to finally hack this thing and give us custom ‘apps’.