Firefox 2 Release Candidate 1 (RC 1) is a preview release of the next generation Firefox browser and is being made available for download to Web application developers, the testing community and users who want to get a sneak peek at the next version of Firefox. Please note that at this time, users should not expect all of their extensions, plugins and themes from previous versions of Firefox to work properly.
Download: Firefox 2.0 RC1 | Multiple languages available ~18 MB (Freeware)
View: Release Notes
Link: Neowin Discussion