A few days ago, a post appeared here that Firefox 3.6.4 had gone final (and it certainly appeared to many of us that it had).
So much for perception but I did promise an update.
It appears that anyone that had the Firefox 'Lorentz' beta loaded was upgraded to Firefox 3.6.4 beta ... despite that fact that the beta tag did not appear on the upgrade screen.
If all of that isn't confusing enough, if you haven't already read it here or elsewhere, an updated beta of Firefox 3.6.4 IS available for testers and developers here. Note: This is now Build 6 and was released just 2 days ago and ... well .... It's pretty slick!
More information can be found on the Firefox Developer News Page here.