I'm officially forking the discussion from "Simon's Accelerated X" thread as we're working on different approaches to improving render performance and it's starting to become confusing.
*ahem* Hi! Like many others, I'm attempting to write an xfree86 DDX driver which will leverage OpenGLES2 and OpenVG to offload most of the xserver's operation to the GPU. At the moment I'm in over my head, but that's never stopped me before, and it's been an illuminating process thus far learning about DDX driver development.
As yet I'm not even at the point where I'm incorporating the videocore libraries to actually render anything, but as I get a "does nothing" driver skeleton in place I'm hoping that perhaps some of the more experienced graphics hackers will want to pitch in, or at least help answer my questions.
My git hub is here https://github.com/Factoid/xf86-video-rpi
and I have plans to add a supplementary git of odds and ends that are either prerequisites for the driver, or simply assist in debugging. Just stuff to help cut through the hassle of getting setup, since there are few things more frustrating than a project that doesn't just build and run out of the box.
Hope to find some collaborators, or at least a cheering squad in here. Thanks for your time!