edit: it looks like it would allow another software to show up as an Airport Express in iTunes, thus becoming the potential target of streaming audio over WiFi from iTunes. But am I right?
This means you will be able to easily send audio to other rooms in your house with something like XBMC running on a PC, nettop, or netbook.
edit: Just to clarify - previously you could do this:
iTunes -- stream to --> Apple Airport Express
3rd party software -- stream to --> Apple Airport Express
Now you can do this:
iTunes -- stream to --> 3rd party software/hardware
If so, Apple and this hacker are about to be lawyered hard by the MPAA.
How is this all that ground breaking from what you've been able to do with Rogue Amoeba apps for a while now?
"Airfoil Speakers works pretty much like an AirPort Express from the point of view of Airfoil. It advertises its services over Bonjour, then uses the same AirTunes 2 protocol that Apple uses. However, despite using the same protocol, iTunes won’t talk to Airfoil Speakers. iTunes uses cryptographic authentication to ensure that it only talks to real AirPort Expresses, and we weren’t able to mimic that. Until Apple removes those checks, Airfoil Speakers will only work with Airfoil 3 and Airfoil for Windows."
In fact, I don't see how this private key getting "outed" is going to hurt Apple at all in any countries where things like DMCA exist.