So, Amazon's shipped my 20GB Karma. Around the same time, I was browsing the iTunes Music Store, and very nearly bought several tracks before I realized that I didn't know if Karma supported AAC (it doesn't).
It's previously been stated that AAC is feasible on the hardware, but that it would require Dolby licensing fees. Ignoring the fact that Apple's AAC has DRM, I'd like just to say that I'd certainly look forward to even "regular" AAC support on the Karma, and would pay for the upgrade to do so.
I mean, I had to pay $30 to get QuickTime Pro, and another $20 to be able to have MPEG-2 support in QuickTime Pro. I suppose that means I'd pay another $49 for Karma AAC support. Bonus points for Apple DRM support, and Mac integration in general.