This is the second failed attempt to pull version 1.4 of the Resize and Rotate extension into the X.Org Server. Originally, RandR 1.4 was supposed to be in X.Org Server 1.9. RandR 1.4 was merged into X.Org Server 1.10 with per-CRTC pixmaps support and other changes, but just last week it was dropped.
In trying to finally get RandR 1.4 out the door with X.Org Server 1.11, Keith Packard initiated this mailing list thread.
Besides bringing the much talked about per-CRTC pixmaps for providing multiple scan-out buffers, RandR 1.4 also adds support for sprite position and image transforms and a request change for CRTC configurations, which can reduce screen flickering and make it easier for NVIDIA's developers to finally implement RandR 1.2+ support within their binary driver. This version though does not provide per-output DPMS controls or any multi-GPU improvements.