I'm thoroughly enjoying my newly acquired Airport Express to bang all of my iTunes music out through a proper hi-fi than my scabby eMac speakers, or the now equally rubbish sounding iSub/tower combo. This whole PCM audio beamed across the house lark is fab, I recommend.
Just to try to bring it back vaguely on topic, I'd be intrigued what people think of the potential using the technology for other applications (it seems obvious that in time, Apple is going to roll it out to other key apps - DVD Player, Quicktime, GarageBand etc. spring to mind), say MacMAME for example....
Imagine sitting in a darkened room, playing Star Wars in MacMAME with the sounds from the arcade behind you, as per the old sit down cab....
Simon