Hi Boris,
I've never mined on GPU's, and I agree with the unprofitable bit, it wouldn't get anywhere near the 80Gh/s I currently do..
I do know people still mine with GPU's but I suspect thats simply because they still have the setup, they certainly shouldn't expect to
make any money from it. In fact many current miner software nolonger supports CPU mining, and many are I suspect going to drop
GPU mining in the near future to stream line the code.
I use ASIC's incase your wondering
Compiling bfgminer would be the easy bit I suspect, the problem would more likely be the USB com drivers and/or HID drivers depending on what USB based miners you are using, and the interface chosen.