Now with iTunes prior to version 6.0 there was a great program called JHymn which would strip the DRM from all your iTMS song automagically. Cool! It was built on reverse-engineering work by DVD John and enhanced by other people. Unfortunately, Apple messed around with FairPlay in iTunes 6.0 and JHymn no longer decrypts it.
But wait -- says I -- I have an old Airport Express and it plays my encrypted music just fine! It was made a long time before iTunes 6.0 came out. Is it possible that the music is being transmitted over the WiFi connection unencrypted?
The AirPort Express contains a little computer that can translate mp3, AAC, and AIFF files into an analog output. I know that it only supports certain formats, because I have audio files in other formats that iTunes will play on my computer but not on my stereo. That means that the Express must contain hardware/software that understands AAC. But it would only understand the old Fairplay, not the new one.
That means that iTunes 6.0 is taking out the new DRM before it sends it over the air to the express. And that means it should be possible to write a program that finds that stream of unencryted data and read it back into an unencrypted AAC.