In addition to this morning's release of iOS 6.1.3, Apple has also seeded a new version of its Apple TV software. The update brings the firmware to version 5.2.1, and it includes a number of bug fixes as well as support for the new Hulu Plus app.
Unfortunately, as with iOS 6.1.3, the bug fixes are actually patches for the exploits used in the latest evasi0n jailbreak. So if your Apple TV is jailbroken, or you would like it to be in the future, you'll want to be sure to stay away from this update...