There has been confusion, particularly in Mozilla's own circles, since the Betas were offered. Like Cattiley, I opted for the Beta testing . I have installed the 3.6.4.. It certainly does not refer to it, in the "About" but obviously is, a Beta release. If, in the help, you look at the release notes, this is confirmed - it is staying on the "road map"
But anyway, it tends towards semantics. I am using the Beta, as a full release. It works for me.
Another comment:
http://www.ghacks.net/2010/04/18/fir...beta-released/