First, the best bit. Jobs showed an iPad (running the forthcoming 4.2 version of iOS) being fired up, pressing a few buttons, and streaming its output to a big screen TV via an Apple TV. This addresses my number one complaint: a friend comes to my house, I show them the Airport Express system, I show them the Remote app so they can use their iPhone to control my iTunes... and they ask me why they can't also stream their own music directly from their device. Sure, this is going to be tough on battery life, but it's not like I'm short of chargers. They want to listen to their own music and if you could see inside my iTunes you'd know why. And now they will be able to!
I was briefly concerned that this jazzy new functionality would not work with my existing Airport Express devices. Fortunately, Apple's sneak peak at iOS 4.2 confirms that an Airport Express will be able to receive a stream from any iOS 4.2 device, so more good news there too.
My biggest second gripe is the lack of sync. If I play the same music on two Airport Expresses (that word does not pluralise nicely), one in the lounge and one in the kitchen, they can be out of sync by a second or so. This produces some rather trippy pseudo-echo effects if you stand in between the two rooms. Apple's Airplay page notes "For the ultimate sonic panorama, you can stream your tunes to more than one room simultaneously" -- I'm hoping this means they've put robust syncing into the streaming protocol. Rogue Ameoba's AirFoil software can sync streams to multiple Airport Expresses at once, so it's certainly a solvable problem.
And then there is third-party device support. Apple lists a number of vendors who will be shipping AirPlay compatible equipment, though so far we haven't seen anything from most of them. iHome however is teasing an AirPlay speaker set, although we only get an image and a "submit your email address for more information" link. Referring back to Apple's product info page, these third-party devices will now be able to receive song metadata like title, artist, and even album art and present a much richer interface to control your music.
And finally, the nifty ability to stream video and photo content as well as sound to the Apple TV. Frankly, that alone might make me buy one, despite my recent whining that it is too expensive in the UK and a lukewarm reception from my colleague Mel Martin. I happily paid around £70 for my Airport Expresses and only use them for music streaming. The Apple TV takes that music streaming and adds loads of other features for a modest £30 premium. In the US they are the same price!
To my mind the best reason to choose a single vendor for all your gadgets is so everything interconnects like this. AirPlay is another great way for Apple to make all its kit play well together.