MPEG-LA, the group that oversees patent licensing for MPEG-2 and MPEG-4, says AT&T is not a part of them, but they can't do anything about it and they make no claim to have licenses to all technologies included in the format.
Nero and Pentax have already made deals with AT&T, so don't be surprised if the next DVD burning software you buy has a bump in price for AT&T's taste. You have to wonder how this is going to affect satellite, cable and IPTV companies looking to roll out MPEG-4; we didn't see any of them or set-top box manufacturers listed. Also, no word if their notification letter to included any references to Steve Jobs as a "n00b".
[Via Data Compression News]