Final build for Mozilla's major update of their web-browser Firefox 4 will officially get revealed on 22 March, but as expected the build had already made it's way to Mozilla's official FTP servers and can be downloaded right now.
For users with the older version of the web-browser, Firefox 4 brings in lots of new features, the most notable being a completely revamped new streamlined user interface, enhanced performance, support for newest open Web technologies, hardware acceleration, jet-powered JaegerMonkey JavaScript engine, built-in Sync, restartless add-ons, and Panorama workspace management.