Apple TV as a Remote Speaker
A nifty feature included in the Apple TV “Take 2” software update is the ability to use your Apple TV as an AirTunes speaker. You can now select your Apple TV from the speaker selection drop-down in iTunes to play your music or radio stations through the device.
Just as with the Airport Express, Signal integrates seamlessly with this solution, allowing you to drive the music playing through the Apple TV from anywhere in the house. If you happen to have the TV on at the same time the Apple TV will display album art for the currently playing song too, making for a nice visual compliment to your music.