If you want to watch a movie on your Apple TV, but you want the sound to play through a stereo or home theater system, rather than through your TV, the only way to do that right now is to install a bunch of messy cables that connect one device to the other — and they need to be relatively close together.
In iOS 6 beta 3, however, you can send audio from the Apple TV to an AirPlay-enabled speaker system at the other end of the room wirelessly.
As noted by FlatPanelsHD, in Apple’s latest beta release, the Apple TV will detect AirPlay-enabled speaker systems connected to the same wireless network, and then allow you to choose them for audio output. So you can watch a movie or TV show on your HDTV, while having its audio blasted out of your AirPlay enabled speaker system (or one connected to an AirPort Express).
In iOS 5, the Apple TV only has the ability to receive AirPlay content, and so iOS 6 will be the first time the set-top box is able to send it. This means that you no longer need to switch on your Mac to stream your music to your stereo — you can just access your iCloud library on your Apple TV and stream it from there instead.
There is one caveat, however. AirPlay does not support 5.1 surround sound, so you still won’t be able to enjoy your surround sound setup wirelessly. What’s more, FlatPanelsHD reports that if you have Dolby Digital audio enabled, AirPlay output is very quiet, and so it should be disabled to get the best results.
Hopefully Apple will fix this before the software makes its public debut this fall.