After releasing update 5.1 for second- and third-gem Apple TVs back in September, Apple rolled out 5.1.1 today to Apple TV owners following the public launch of iTunes 11.The 5.1 update includes Shared Photo Streams, AirPlay, iTunes account switching, and more, so we aren’t expecting to discover much in today’s update.

From Apple:

Apple TV Software Update 5.1.1

iTunes Up Next Adds support for Up Next with iTunes 11 or iTunes Match. See upcoming songs when playing music on your Apple TV. Add new songs and edit what’s queued with your Remote or with the Remote app.
Stability and performance Includes performance and stability improvements with the iTunes Store, AirPlay, Netflix, iTunes Match, and wired Ethernet connections.