Back in April Ben Heck modded a PS3 controller to fit inside of an Xbox 360 one. Well now he's decided to flip that and cram an Xbox 360 controller inside of a PS3 one.
The mod includes working dual shock and everything, granted he does still have a couple things he'd like to tweak on it. He left out the headset connector in this particular mod, but intends to fix that next time.
He did include the DS3 buttons on this, which means your friends would notice that something was a bit different. However, it might be nice if he kept the buttons PS3 style. Then again the brightly colored buttons look nice too, just depends on your preference.