The company targets March 22 as the release date at this time, according to a developer post by Mozilla's Damien Sicore.
So far it seems as if the RC is handling the QA process as well. Only one major (Java) bug has been found, which Mozilla, however, did not qualify as a blocking bug. If all goes according to plan, Mozilla will publish Firefox 4 final on March 22 as marketing and It already approved the date. If Mozilla discovers a bug, there will be a second RC and the final release date will be delayed.
At this time, Mozilla is about five months behind schedule. Before the end of June, Firefox 5 is scheduled to be rolled out.
Microsoft released IE9 late yesterday, which increases the pressure on Mozilla to release its next-generation browser.
In the meantime, get Firefox 4.0 RC1 here!