First from my original post ...
Gordon's Tech: Remote control of iTunes and AppleTV: will AirTunes return?
... Son of a gun, it works. It really, really works. I've been controlling my upstairs Library from my iPhone, streaming music to my AirPort express, and listening to speakers in two rooms. Years after the AirTunes hype died off, Apple finally delivered.
There's even intriguing/worrisome support for multiple libraries, which brings me to a comment from someone who's gone another step beyond me (note this only works if you wisely avoid the plague of DRM)...
The key bit of good news is that I could control my Library even when iTunes was running in a 10.4 background session.
It gets beter though. From Jan ...
It looks like Remote with iPhones/iPod Touch and AirTunes is the solution for for the multi-room audio setup I was waiting for years to come.Note Jan has one set of files, but 3 libraries. So each user can sync their iPod or iPhone with their own account and save their own Address Book and preferences, but share one set of music.
I installed several AirPort Express boxes with AirTunes in the rooms and installed 3 users on a mac mini with fast user switching on. All users have their own iTunes setup and have access to a central NAS Server with all the MP3 files. This won´t work with Windows because Windows won´t allow fast user switching running iTunes !
With this setup every family member is able to hear their music independently on different AirTunes outlets. It really works !
Excellent. I'm going to do this one day. Note it requires that the music file be on a NAS. I knew I'd want one of those soon.