http://releases.mozilla.org/pub/mozilla.org/firefox/releases/2.0b1/ I've been using it today on Windows and OS X and I'm impressed so far. It's could stand to be a little more stable, but it is still beta. As would be expected, it broke most of my extensions but not all. For the most part it looks about the same except it now has the "close tab" x-button on the current active tab itself instead of all the way to the right. Also, now, when you close a tab, it automatically returns focus to the previous tab regardless of if it's next on the left or not. There used to be an extension for this feature and I think it rocks that they made it default behavior. And, upon apparently misspelling "behavior", it seems the new built-in spell checker is also good to go. This looks like it will be a good release.