Ubuntu Linux 8.10 release candidate beta version has been released and available for download from mirrors. The final stable version will be released on October 30th, 2008. But, if you would like to test latest version try out Intrepid Ibex RC beta version.
Firefox 3 is based on the Gecko 1.9 Web rendering platform, which has been under development for the past 34 months. Just released RC2 of version 3.