One of the new features of Firefox 2.0 is the ability to scroll through your open tabs using arrows on either side of the tab bar. Today I noticed that if you have two-finger scrolling enabled on your MBP, after hitting either of the arrow keys, you can two finger scroll horizontilly to scroll through the open tabs. This only works when there are more open tabs than can be seen in the current window. I don't know how useful this is (I generally don't have 15 tabs open) but hopefully someone will be able to use it.
Note that this scrolling keeps the current tab selected, but you will be able scroll through the open tabs and see the name of the page opened in that tab. I also used this on a MacBook Pro using an Intel-optimized build of Firefox 2.0. I would assume that this would work the same in the standard Firefox 2.0.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20061223154012501