What's in a name? It's actually 6.5-ish, stop worrying about the numbering system.
The only practical importance, except for corporate use, is whether or not your own set of plug-ins remains compatible, and by that measure FF 7 and 8 have been the most trouble-free browser updates ever for me.
It don't matter what number system they use, they don't improve it. i used to love Firefox,but it just got slower and slower with more and more bugs, they seem to be more bothered about what it looks like than how it works.
Desktop machine now powered by windows 7 pro 64bit , laptop by ubuntu
On ADSL24 using C&W network.