Lost in the hoopla of all the Macworld giddiness is a cool new feature available to users of Apple's Airport Express.

Previously, you could only use the AirTunes feature to broadcast music to a single AirPort Express base station, but in the AirPort Express Firmware Update 6.3 Apple has quietly added the ability to stream iTunes to multiple AirPort Expresses simultaneously.

Can anyone tell me why there's no mention of this on the AirPort Express Firmware Update 6.3 page? It's a major freakin' feature!

After upgrading your 'Express to the 6.3 firmware there's a new option for "Multiple Speakers" in the AirTunes drop-down list in the lower right edge of the iTunes window. When you select it you can then select the multiple speakers to stream to, including "Computer." That's right, in addition to multiple AirPorts you can also hear the music out of the computer's speakers at the same time - another major feature! The new 6.3 firmware also syncs music on the computer and the remote speakers.

On caveat: the multiple speaker function uses UDP and you'll need to allow it in the Mac OS X firewall (you do have it turned on, don't you?):

System Preferences > Sharing > Firewall > Advance > Uncheck "Block UDP Traffic"

While it's not the upgrade I hoped for in my Macworld predictions article nor is it as full-featured as Rogue Amoeba's Airfoil 2.0 software (US$25) it's a step in the right direction and it's free!