Apple TV owners no longer need to choose between jailbreaking or running the recently released iOS 5.1 update, now that FireCore has pushed new versions of Seas0nPass (0.8.3) and aTV Flash (black) (1.4.1).
Currently, the jailbreak is still tethered, so if you should have to reboot your hockey puck, connecting it to a computer and repeating the process will be required. Unfortunately, the tools won’t work on the new third generation Apple TVs yet, and even on supported hardware some plugins, like Plex and XBMC, are still listed as not working. All the details can be found beyond the source link for both the free Seas0nPass jailbreaker and $29.95 aTV Flash that adds more functionality.(Engadget)