I was just wondering if the new version of AU (cs6) needed to use SoundFlower to record audio, such as youtube, itunes, vlc etc from on the computer.
Hopefully not, but just curious.
Also, is there a "play-through" on the recording facility in AU too?
I'm not a Mac user but I can tell you that Audition doesn't have anything to do with that sort of audio routing--it depends on what your computer or audio interface gives it. This hasn't changed between CS5.5 and CS6 so if you needed Soundflower before I'll guess you still do (unless something has changed in the Mac OS in the interval.
(Similar things go on in Windoze--bowing to pressure from the copyright holders, Microsoft and the computer manufacturers have removed the native facility to record "what you hear" from the computer so I assume this is the Mac manifestation of the same thing.)
I can verify that yes, there is no built-in support is OS X to route the output stream to an input channel. Soundflower does a good job of enabling this ability for Audition and other audio applications.