I don't believe this has been posted before, but I found a second audio connector on my board.
See Image: http://www.mbmd2002.com/simages/audio.jpg
Look at the first picture, where the existing audio connector is, and look below it. Now, look at the rear shot, and notice they're meant for the same connector. What might this do, possibly another audio out, line out, or microphone? I don't honestly know...