Actually, the original one is heavier. Also, the analog sticks on the original one has more tension than the fake ones. Wires on the original are much longer, and the buttons are more 'juicy' to press than the 'clacky' kind on the fake ones. And most importantly, all the buttons (with the exception of L3 and R3) are pressure sensitive, so test it out on racing games like GT4.

And why is this 1 and a half year topic resurrected, anyway?

There is no such thing as a fake Sixaxis/Dual Shock 3.... unless there's a nice long wire sticking out of it.

Wireless/motion sensor controls are probably too costly/complicated to pirate effectively.