If you're a 2nd- or 3rd-gen owner of an Apple TV, you should be receiving an update for iOS 5.1. Apple rolled out a slew of new features for its media-streaming device, the most important of which include shared photo streams, iTunes account switching, and some added AirPlay functionality.
The shared photo streams feature allows you to view the photo streams that you create on your iOS devices on your Apple TV. You can update your photo collections and even invite friends and family to view your photos and comment on them. Also, public photo streams can be viewed through Apple’s iCloud site and now Apple TV devices.
Some of the new AirPlay features are impressive as well. You now have the ability to send audio from your Apple TV out to devices that support AirPlay, such as compatible speakers, AirPort Express devices, and other Apple TVs. You can now also password-protect AirPlay access with an on-screen code, so that no one else on your WiFi network has access to your content.
Another great feature they've added is iTunes account switching, which lets each member in your family have their own music or movies libraries on the Apple TV. The update brings the ability to swap between accounts quickly right on the Apple TV. Of course, you could just have one big library that combines all of your family's content, but we know how stingy some family members can be.
The iOS 5.1 update also includes subtitle support, movie trailers, more advanced networking options, and general performance improvements and bugfixes. If you don't yet have the update, you can grab it now by going to Settings > General > Update Software on your Apple TV.