The Mozilla Foundation have recently released Firefox 3.0 RC3, which is one step closer to the final release. You can check out the release notes for Firefox 3.0 RC3, or go straight to the download page. Now remember that these builds are for testing purposes only, so enjoy.
Firefox 3 is based on the Gecko 1.9 Web rendering platform, which has been under development for the past 34 months. Building on the previous release, Gecko 1.9 has more than 15,000 updates including some major re-architecting to provide improved performance, stability, rendering correctness, and code simplification and sustainability. Firefox 3 has been built on top of this new platform resulting in a more secure, easier to use, more personal product with a lot more under the hood to offer website and Firefox add-on developers.