Information on USB Audio
There are but it might be over kill for you depending on what you want to do.   Here's a link to the USB.org spec about audio devices http://www.usb.org/developers/devclass_docs/frmts10.pdf

That's probably not what you're looking for.  It looks like they're saying that now they'll support you plugging in a USB audio codec and your Android device will recognize it and add it as an output you can play sound through.  They have USB OTG so in theory you could plug any USB audio chip/device in and play sound through it.   

There are a ton of USB audio codec chips out there if you're trying to build a piece of hardware.  TI makes a few parts just google for USB DAC.

If you just want to write some software that uses it, I think it'll just show up as another audio device for you.

Oh and here's a cool link to a forum topic where some people are messing around with it.  The pictures probably do more for an explanation.  http://androidforums.com/samsung-galaxy-s3/547033-usb-audio.html

Good Luck