I was thinking, couldn't you have a program take the AAC files and make an audio CD iso? Last I checked only iTunes can burn the AAC files to audio CDs, but it's likely someone could find a way around that pretty easily. It would be easier than making another PyMusique, probably. I guess it would be possible to create a virtual cd-burner, much like current virtual drives, but it has a setting to produce isos from whatever program accesses it, rather than burning. After making an iso you could simply mount that and convert from it. This would also enable you to convert MORE songs at a time, as the audio cd iso wouldn't necessarily have to be only 700 megs (depending on what you use to mount it I guess). It would also keep the quality slightly higher, completely digital re-encoding rather than digital to sort-of analog cd back to digital.
If anybody came out with this, I would certainly be grateful, as it would save both time and cd-rs. You listening, DVD Jon?