From Fedora Project Wiki

Will this use a separate profile from default firefox in fedora? -- It doesn't, you need to create a new profile yourself if you wish to separate them, and also change the launchers to use that profile. - pankaj, October 24 2010, 10:00 UTC

Now Firefox 4 is released when will it be available through regular updates. Any Ideas? -- It won't be available as a regular update for Fedora 14 at all. It requires a newer version of Xulrunner and that involves rebuilding, testing and pushing out dozens of updates - Rahul Sundaram