Rather than blast the idea I'd suggest looking into open source mobile drivers like
http://limadriver.org/ and the Raspberry Pi's GPU
http://www.broadcom.com/products/BCM2835It might have an ARM onboard but it's not mindblowingly fast. There are also CPU-less GPUs from Broadcom that could be used. So it might be feasible but it would probably be a large project for a hobbyist.
