Quite some time ago the Firefox team announced to release versions 5, 6 and 7 this year. Like steroids, the team is speeding things up starting with the release a Firefox 4 RC. After release of the Firefox 4 beta10, many patches were fixed and the team still has some more issues to take care of before the RC which is shecdule to release on next friday the 25.
According to post to the Mozilla Development Planning team by Damon Sicore, Sr. Director of Engineering
…final push to get Firefox 4 to release candidate…Let’s finish these last few bugs and aim to finish RC by Feb 25th.
You can test out the beta version till then..