Shortly after the release of the iOS 6.x jailbreak tool evasi0n, FireCore rolled out a new version of its Seas0nPass utility to support the latest firmware. Folks with a second-gen ATV on iOS 6.1 (5.2) can now enjoy an untethered jailbreak.
Up until now, though, most people (including myself) have been reluctant to upgrade to the new software because many Apple TV apps still don't support it. But you'll be happy to hear that XBMC has just taken its name off of that list...