Jon Johansen (of DeCSS fame) has released code that strips DRM from Apple ACC audio format.

Mac Rumors has the straight dope:

] The application clearly piggybacks off of Apple's
] Quicktime player and patches the "quicktimempeg4.qtx"
] file of Windows' Quicktime. It then outputs this "raw AAC
] data" to a file while the original AAC file plays under
] Quicktime. The proposed theory is that the application
] intercepts the Decrypted AAC data from Quicktime after
] authorization has taken place, and saves out the
] resultant decrypted (de-DRM'd) AAC data.
]
] Based on limited testing from one user with Quicktime 6.4
] under Windows... the application does create DRM-free
] ".aac" files when Protected AAC files are played through
] Quicktime. These output files, however, are unplayable in
] their raw form in most players. The reason for this is
] that these files represents the true "raw" AAC data that
] has been passed through to Quicktime to play. All header
] information has been removed. To create playable files, a
] further packaging of the files is required to add the
] appropriate MPEG headers. But the application does work
] as suggested -- stripping DRM from your protected AAC
] files (though is not of any practical use in its current
] form).

"QTFairUse" .. Great name. Very to the point.

Umm.. I think this is where I say "here we go again.." ??

It will be interesting to see how Apple reacts.. Between this and the current iPod dirty secrets thing, they have a fair amount of pressure on them. I hope they don't do something stupid.

They should have been expecting this to happen at some point.. They likely have a strategy thought out already for dealing with this.

Mac Rumors: QTFairUse - iTunes Digital Rights Management (DRM) Circumvented?