2009 was mainly to fit the regressions that 2008 made (it's the part of Firefox's new marketing drive, they've lost the dots when talking about it on promotional website, more sleek apparently), I think they were mainly caused by making it compatible for the new mac.
Anyway Firefox 3 Beta 1 is almost ready, yesterday it had only 1 blocker left and was expected to be fixed by the end of the day, as soon as it comes out officially I'll make a post about it and explain significant changes and changes still to come.