"Today we have our first Firefox 1.0 candidate builds available for testing. You can get these test builds from FTP. If you've already downloaded 1.0 PR (the "feature complete" preview) and you're not really interested in testing and bug reporting, then you should probably stick with 1.0 PR for a couple more weeks and upgrade when we release the official Firefox 1.0.
The release candidates include about 250 bug fixes since Firefox 1.0 PR and we'd appreciate any feedback around any of those areas..."
In case you are simply too much of a Firefox fanatic and don't want to it until November 9th for the official 1.0 public release, you can have a go of the first release candidate here. Here are some additional release notes as well.