A post from the discussion, “Firefox 4 has gone, will be released by March 22nd” in mozilla.dev.planning

Two problems got out (funny, almost immediately after Damon sent his email), which led us to make two very small, very isolated corrections in order to better protect Firefox 4 users. These corrections will be included in the version of Firefox 4 RC2 for Windows, OSX and Linux (which should be available tomorrow) and Firefox 4 RC1 for Android.

Our schedule will not need any changes. We still expect the final version of Firefox 4 for Windows, OSX, and Linux to be released on March 22, as planned.