I have been using "Firefox 4.0b8pre" (with Jaegermonkey!) for weeks. It's really been a pleasant experience, fast load times, nice UI, and few if any major bugs. Perhaps I just caught a good nightly, but nonetheless, this news then comes as surprising to me.
I worry about delaying the Firefox release until next year (where FF4 seems as much about catching up to the competition as it is new features), but if it allows this chart to cross the green line, then I'd say that would be some huge bragging rights: