I've ordered a few of those microUSB to USB OTG cables thanks to Negakinu's advice. The ones I orderered specified they're for the SGS-i9000 (I have a T-Mo Vibrant, an SGS phone with the good Wolfson DAC)...
I'm eager to see how this will all play out. I am running CM9 nightly with Glitch Kernel (supports VooDoo Sound) I usually use n7player, but have a license for Poweramp, should it be necessary for getting the OTG function working.
Also starred the issue in Android for google code. I remember when they still didn't support *.flac... Wake up and smell the music, Google. LOL.
I'll post my success (and hopefully lack of) or failures here.
CM9 won't work. ICS 4.0 doesn't have USB audio out. You need CM7.