If you found this report interesting, you may also find John Hayward-Warburton's writeup to be particularly interesting. RealNetworks themselves did a writeup on MS Audio here. Robin Whittle did an aboslutely incredible comparison of AAC, MP3, and VQF a few months ago. Robin also covers lossless audio compression in great detail. Panos Stokas ran a nice informal series of tests on his page. You could also look at ISO's AAC listening tests (requires adobe acrobat) to see a very formalized set of tests.

And, of course, if you found this writeup interesting, maybe you'd like to look at the rest of <david.weekly.org>! =)