People at Doom9 and Xboxhacker have been picking apart the firmware on the Xbox 360's HD DVD drive. By using a patched firmware, they've been able to expose Volume ID's without AACS authentication.
More interesting is that someone found a bug in the firmware which lets you view Volume ID's without the patch.
http://forum.doom9.org/showthread.php?p ... post987050
At this point, I'd say that AACS is pretty much cracked. The AACS LA could revoke the Toshiba drive being used in the Xbox 360's HD DVD addon, but I really don't see that happening.