There was not really any doubt that the new Apple TV was indeed running on iOS. But in any case you did have your doubts, that should be put to rest now as we see that Apple has uploaded a new version of iOS 4.1 to their servers that references Apple TV. The software is identified as AppleTV2,1 and is noted to be of 4.1 version. You can download it from here but that does no good unless you will need to restore the OS.
More interesting since the discovery is the fact that this new iOS for Apple TV is jailbreakable with the recently discovered SHAtter exploit. If you are not of what SHAtter is, it is worth noting that this is a bootrom level exploit that can only be patched by releasing a new version of hardware. This means that the new Apple TV can be jailbroken for life with this exploit. MuscleNerd from the iPhone Dev Team writes,
“It’s looking like SHAtter is going to be the gift that keeps on giving. Even though the new AppleTV isn’t yet in people’s homes, the firmware is available on Apple’s normal public distribution servers and SHAtter has been used to decrypt its keys! The main filesystem (“Mojave8M89.K66OS”) key for 018-8609-066.dmg is:
If you’re familiar with vfdecrypt, you can use that key to decrypt the image and mount it.”