Re: What are pinch harmonics? and what pick ups does it well?
You have to find them - as has been said, you kind of dig your thumb into the string a little as you pick. You have to pick in particular places too - if you have a strat, try just to the bridge side of the polepieces on the neck pickup, I find that one reasonably easy to find.
There are several positions where you can pick and get a pinched harmonic (each sounding different), and these positions do vary slightly on different strings (I find they tend to move in the bridge direction a little as you move from the lower strings to the higher strings).
I have to admit I'm no expert on them (particularly the screaming metal-type pinched harmonics some players seem to get out of the wound strings - wish I could do them better). I find it harder to get a decent sound if I'm playing with a scooped-mid sound. Dialling in the mids seems to help me voice them a bit better. I also find it easier when going throught the distortion channel than the clean channel.
EDIT: learn the intro to 'Revolution is my name' by Pantera - I (try to!) use that one to practice pinch harmonics, as you have to play them on different strings and vary position.