Damon Sicore, Mozilla's Director of Platform Engineering, told developers via a mailing list (which you can read here) that the final version of Firefox 4 should be ready to ship by the end of February, but not before another beta and a release candidate come out first.
Sicore mentioned that at the moment they have around "160 hard blockers remaining" and in the past it has usually "taken [them] six weeks to reach RC once [they] have 100 blockers left." That puts the typical first RC at the end of February. But Sicore was insistent, claiming they "must press hard now." In fact, his plan is to finish the RC by the beginning of February and to ship the final release by the end of the month.
All of this, riding on the coattails of another beta release. Firefox 4 Beta 9 was issued today but isn't currently reachable through the frontend channels. Thanks to torrentthief in the forums, you can find the new beta by going through Mozilla's FTP pathway. The new beta reportedly fixes a variety of 787 different bugs, but there are still more to remedy.
Sicore claimed that before a release candidate, they will (of course) release another beta which will hopefully bring the bug count down to zero. If that is not possible for the next beta release, "then [they will] repeat, deliberately."
[Image credit: mozilla.com]