Firefox 4 Beta is out. Are you a beta tester ? If so, you have some nice features listed out there to try out.
Link: http://www.mozilla.com/en-US/firefox/beta/features/
Now the million dollar question: Is FF4 Mature enough to be migrated to?
And after searching around a bit, I think, people still have problems with latest beta version. So hold on to your horses, still a set stable beta version of Firefox 4 is out.
Related links:
1> Should I migrate to Firefox 4,
2> Add-ons that work with Firefox 4.