Firefox 10 Extended Support Release.
http://www.mozilla.org/en-US/firefox/organizations/faq/
Blah blah not for individuals blah blah....
If I used firefox I would be using this version. Supported for a full year and will still get all of the critical security updates and none of the other garbage.
I'd really love to see this version just take over so they realize that they don't need a new version every 6 weeks. Most linux distros update twice a year and I find that even with that they are too frequent. If you download one version halfway through the life cycle it won't be long before the next one is released.