According to the Mozilla Blog, the Firefox 3 release and download day is today (June 17, 2008) and will begin around 10:00 a.m. PDT, which will be 12:00 p.m. CDT (our time). You still have time to pledge that you will download Firefox 3 on the first day of release.
The word on the street is that the final release will be exactly the same as the RC3, which I have been using lately and encountered very little problems.