"The" pinch? Kazz, almost the entire last minute of the song is nothing BUT pinch harmonics. I listened to La Grange just now and from the point where Billy Gibbons starts laying them on, I tried counting how many are there. I lost count somewhere around 35.

oke:
Here, listen from exactly 2:30-3:20 on this and you should be hearing them all over the place.
http://www.youtube.com/watch?v=zQVmA5EW7vM
Just remember, Zakk is kind of his own thing and his are really pronounced. A lot of that has to do with what I was talking about earlier: what he does with them once he picks them; a high gain harmonic followed by that wide vibrato (and a lot of Wah in there too, many times). Billy Gibbons from ZZ Top, on the other hand, is just doing full step bends everytime he hits one. It's an entirely different sound.