The Apple TV was one of my favorite purchases of the last year. It isn't just an audio component but that is certainly one of its many features. The Apple TV is a box that you hook to your widescrreen HDTV and it allows you to access files on your iTunes both music and videos by syncing or live streaming.
I purchased the 40 gig version with hopes that the streaming would work well enough that I wouldn't need the larger unit and I was plesently surprised that I am able to stream even video seamlessly over my G network. It supports wireless inside the box up to the N specification and has an ethernet plug on the back also.
When you plug it in for the first time it steps you through a couple of screens and then gives you a code to put into your iTunes library on your computer (to authorize sharing). As soon as you put that in you can choose what items you want to sync to the Apple TV of if you just want to stream pick your computer under "sources" from the main menu.
From the main screen you can access your music library, videos, tv shows, pictures and youtube. All screens are very sleek and classy looking featuring album artwork and reflections. Slideshows of pictures look amazing on an HDTV and our favorite feature is actually the screensaver that brings up random floating pictures from your library.
The YouTube portion actually access a much higher quality video archive (H.264) and many videos look broadcast quality.
The only slight issues I have with it is it will ocassionally lose sync with my network and I have to re-select my iMac as the source component but I believe it may be due to a wireless speaker system interfereing with the connection.