There is not really the need for HDMI sound in gaming machines, but for HTPCs, it is crucial. Auzentech is on the right track with their HDMI X-Tension Sound Card. This is a sweet looking sound card that runs on PCI-E, which at this point is a massively underused specification. I am betting we are going to see a lot of competition from the other high-end audio card manufacturers in the not too distant future.
According to Audio Junkies:
The HDMI X-Tension includes full support for all 8 channel linear PCM digital formats, including Dolby Digital EX/Plus, Dolby TrueHD, DTS ES, DTS HD High Resolution/Master Audio, and DVD-Audio. PCM Stereo up to 24bit/192kHz is also supported. The only multichannel digital format not present is DSD, which is not necessary as there are no SACD computer drives. The HDMI X-Tension is expected to ship in Q2, 2008
Q2 is not that far away, so we won’t have to wait too long to see what these are like. No word on pricing yet.