http://www.mozilla.org/projects/bonecho/releases/2.0b2.html
"Firefox 2 Beta 2 is a developer preview release of our next generation Firefox browser and it is being made available for testing purposes only. Firefox 2 Beta 2 is intended for Web application developers and our testing community. Current users of Firefox 1.x should not use Firefox 2 Beta 2 and expect all of their extensions and plugins to work properly."
I don't care -- I use it anyway, and the occasional browser crash doesn't bother me too much. This version has gone through a visual overhaul, which makes it look nice and refreshing, so there's no need to change it. I can't wait until it's officially released!