The Apple TV device has already been jailbroken thanks to the works of the iPhone Dev Team who managed to come up with a Jailbreak tool called SHAtter for the newly released Apple TV, even before it reaches most of us.
SHAtter has been tweaked to work on the Apple TV, which unsurprisingly shares the same platform as the rest of the iOS family (iPod Touch, iPhone and iPad).
The hack has been carried out on a firmware restore file that has been posted by Apple and which contains the entire OS. The Jailbreak tool will allow users to install apps on the device as they would on any other iOS platforms.
According to Will Strafach from the iPhone Dev Team, the new Apple TV OS is a combination of the old AppleTV OS and iOS which means that hacks that worked on the old Apple TV are likely to work on the new one.
The fact that Apple TV OS binaries are marked as iPad compatible would mean, in theory, that the Apple TV is Airplay-compatible.
You should therefore be able to move seamlessly from one screen (Apple TV) to another (iPad or iPod Touch) and continue watching video content regardless of which device they use.