I wish apple was more open.
Anyway, I like this AirPlay thing a lot.
But I m not going to buy all my electronics again for this.
The first device that will let you connect your stereo to airplay is going to sell a LOT!
I know Airport Express can do that! But AE can do a lot more things too and cost 100 $/e! Something smaller, like a wifi-airplay adaptor from a 3 party with outtax...
It's already out. It's called an Airport Express. AppleTV does it too.
What will be amazing will be if apple allows the video component to be transferred as well as indicated potentially here, effectively eliminating the need for the AppleTV if you're building from scratch (you might as well just buy a receiver that supports it).