Rick Bergman from AMD said the RV6xx will function as a sound card too. The RV6xx will have HDMI support, the ASICs implement a HD Audio controller as well as the rendering core, allowing the board to pass out protected path audio along with video on any HDMI ports the final products might sport.
It's not sure whether the ATI R600 will have the same capabilities, the slide seems to suggest this is only vor the RV6xx series.