This article from Daniel Eran on the capability of Apple TV in relation to 5.1 audio is lengthy and concise.
Thanks to Merlin Mann who has a vested interest in the technology working properly now and who is in opposition to the Scott Bourne’s of the podcast world.
I think Merlin or Ze Frank could be the stuff that makes the Apple TV type device a real winner. Just as Dire Straits helped make the CD a standard for audio by being one of the pioneers of digital recording.
When “Brothers in Arms” was released most CD’s were produced by recording on analogue equipment then mastering as digital. The quality of that CD made me look for material that was recorded digital. It makes sense that as more people have HD screens and AppleTV they will look for 720p content online. At present the podcast is the best bet to find it.