A patch has finally been written for supporting HBR (High-Bit-Rate) audio over Intel HDMI devices on Linux.
Written by Wang Xingchao of Intel, Takashi Iwai just pulled in support for enabling the HBR feature on Intel CPUs. The HDMI High-Bit-Rate audio support required some changes to properly support this feature, which is now in Takashi's Git repository and should be pulled for the Linux 3.7 kernel.
HDMI HBR allows for supporting TrueHD and DTS-HD MA formats. The patch for those interested can find it from this commit