HDMI 1.4a was introduced back in 2010 and introduces a set of mandatory 3D formats for broadcast content and the "Top-and-Bottom" 3D format, as basically a means of standardizing 3D support across HDMI.
The newly-published patches allow for Stereo 3D mode support within the Intel DRM driver. There's three Linux kernel patches needed to parse the HDMI CEA vendor block for the necessary information, expose the 3D format flags in modes, and then to set a new property on HDMI connectors for supporting stereo 3D. Libdrm changes were also published to sync the new mode flags, and then lastly there's a new "testdisplay" addition to the intel-gpu-tools package for testing the Top Bottom and Frame Packaging modes.
Those interested in learning more about this Intel HDMI Stereo 3D support for Linux can find the current patches on the intel-gfx mailing list.