David Airlie has been working on the X.Org support for GPU offloading (e.g. NVIDIA Optimus-like configurations) and USB GPU hot-plugging (e.g. the DisplayLink adapters). David made DDX driver API changes, hacked on DRM PRIME, and then added provider object support for RandR 1.5, among other work.
With the very latest Linux kernel and X.Org bits, everything is falling into place for GPU offloading and GPU USB hot-plugging. Below are two videos that were uploaded by David Airlie to show off the technologies that are new to X.Org.