Being used to the 3-finger-swipe functionality to navigate within Safari and other Apple applications I wanted Firefox to behave the same way. Safari is really a great browser but not used by many users. To test my websites in terms of design and functionality I use Firefox and IE as well.
Unfortunately the Trackpad gestures are not working with these browsers. After some research in Google I finally came across a great piece of software:
MultiClutch brings you the MultiTouch gestures to any application and lets you control the action behind every gesture. It embeds within the System Preferences Panel and is really simple to use.
Here is an example configuration for Firefox to use Swipe for back and forward history navigation: