This DRM render node work has been the work of David Herrmann over the summer with financing by Google's Summer of Code. The strategy of the project comes down to splitting up the kernel driver mode-setting and rendering interfaces so they are no longer as intertwined.
Version 2 of the patches were posted last week and already the Intel DDX has adopted render node support. "Render nodes allow clients full access to off-screen rendering and GPU offload, without assuming any master responsibilities (for device and display management). As they have a more limited interface, they can be used in a more permissive manner."
David Airlie has merged the experimental DRM render node code into his drm-next Git tree, which is what he'll be pushing to Linus Torvalds as the DRM feature merge for Linux 3.12.