What version of FF, out of curiosity? I'm using 3.6 and some basic multitouch gestures work for me. In fact, the three-finger swipe up/down to go to the top/bottom of a page doesn't work in Safari 4 for me, but works in FF :-( Strange.
Surprisingly Safari doesn't have the 3 finger swipe feature. I used Multiclutch to add that and do some other gestures like rotate left and right to switch tabs.
I recently just switched back to Firefox and I have to admit it's a much better experience. With Multiclutch, all of the gestures are still here and the add-ons and the smart address bar make browsing a better experience. Less crashes too.