Render-nodes were an experimental Linux 3.12 feature that allows user-space to use non-privileged GPU commands without any DRM-Master setup. The primary use-case for DRM render-nodes is off-screen rendering (GPU offloading), GPGPU clients, and other render clients. DRM render-nodes was already covered at length in several Phoronix articles so check them out if you need a refresher. For the past few kernels the DRM render-nodes feature has been supported by the main Direct Rendering Manager drivers.
Herrmann, who was one of the original render-nodes developers, is now looking to enable this kernel feature by default. David sent in the patch this morning that would enable the feature unconditionally and could be merged for the Linux 3.15 kernel. David Herrmann wrote, "We introduced render-nodes about 1/2 year ago and no problems showed up. Remove the drm_rnodes argument and enable them by default now."
Linux 3.15 should be another great kernel cycle that will begin in just a few weeks time.