R600 has two DVI's and at least one of them can output fully HDMI compatible HD audio and Video. That is one of the secrets of the R600.
The cards will bundle the DVI to HDMI dongle and it will make this possible. We already told you before that these RV6xx parts are fully HDCP and HDMI compatible.
The audio part is also done on the R600 chip and we already told you about it here. RV610 and RV630 parts will also be capable of doing it.