Comment here indicates no:
http://news.ycombinator.com/item?id=3166268
If AAC costs $1/device to implement, who exactly cares that the code is "opened"?
(1) Apple Lossless, not AAC. Apple is not open-sourcing their AAC decoder, which is part of QuickTime.
(2) The Apache license grants a royalty-free patent license.
Comment here indicates no:
http://news.ycombinator.com/item?id=3166268
If AAC costs $1/device to implement, who exactly cares that the code is "opened"?