nice,
i got tinygl working a while back and for simple stuff its extremely feasible, i don't see this as being any less effective

for pure performance, how much of a rewrite for 3d on a YUV surface.. ?
(hint, start with greyscale only)
at the moment, there is a 20-30% graphical advantage by using it, even more for grey only. thats across the board - less blitting and also less to transfer to the hardware.