Apple has pushed out Apple TV software version 5.0.1 (4224), aka iOS 5.1.1 (9B206f). The update applies to both the 2010 Apple TV (720p) and 2012 Apple TV (1080p). No new features are shown following the update, and no new services seem to have been added, so this could well be a bug fix and performance enhancement release.
(And once again I'll add -- how it helps anyone, inside Apple or outside, to refer to the same software by different versions numbers, is beyond me. Could we please just unify behind the same numbering scheme as the rest of iOS and call it a day?)
To update your Apple TV:
If you have any trouble or need any help, head on over to our Apple TV forum!