I found out about this adapter on the PS forums today and I thought I'd share it with you.
I personally prefer the DS3 because of the stick fluidity and the fact that it doesn't make my hands sweat. But I totally understand the fact that people prefer the 360 con. (If only they made one of these for the DS3+360) There are a couple of little flaws though, it only works wired up and you will lose the pressure sensitivity of the buttons. (If you play Gran Turismo with the X button as a throttle, you might want to reconsider) But if you absolutely hate the DS3 and don't mind compromising wireless freedom, than $50 should keep you satisfied.