Those using Intel's driver with the G35 or G45 series have too been without HDMI audio capabilities. Intel though has now stepped up to the plate and have sent along patches that enable this capability.
Intel's Wu Fengguang has posted three patches on the X.Org mailing list that bring forward this support (one, two, and three). A patch has also been posted on the mailing list for the ALSA (Advanced Linux Sound Architecture) to support the audio codec with Intel's G45 and to report the monitor's ELD (EDID-Like Data).
These patches haven't yet made their way into the respective xf86-video-intel and ALSA driver development branches, but we imagine they will be soon.