The second Release Candidate of Firefox 3 was made available for developer testing and community feedback. If you are already running Firefox 3 RC1, then don’t expect to see any new features because RC2 is all about bug fixes and other under the hood performance tweaks.
Firefox 3 RC2 is available for Windows, Linux and Mac in over 45 languages. If you are already running Firefox 3 RC1, then go to Help > Check for Updates and upgrade to RC2, else just get it from here.
Hopefully, this is the last release candidate before the final release, which is expected to happen at some time later this month.