There are enough pins to carry audio, it's just not included in the DVI specs since that's not the intention. I don't have one myself, but that's how I understand it.

HD621, G98DH, G68ADV, Bc Acoustiqe ACT A3, 5200C DSP33, NuForce Reference 9 monoblocks, 2x SB3's, Velodyne DD-15 & DD-12 Subwoofers and a Meridian sub.