My understanding of Yacoin is that it's generally based off of the litecoin code,
It's forked from NovaCoin, which applied Litecoin's scrypt to PPCoin's Proof of Stake + Proof of Work.
K, thanks. Wasn't paying a whole lot of attention to where it came from. The point, though, is the non-standard scrypt that it's using that's supposedly difficult for GPUs to work with. I don't know if it is or not, but if it is, that's interesting.