Firefox fans rejoice as version 4.0 is now available to download in beta form. Mozilla's Firefox 4 Beta 1 just launched today for anyone interested to download from the company's site. Users of Windows, Linux, and Mac OS X can download the beta which brings with it a slew of new features that includes WebM support. Version 4.0 brings with it an overhauled visual style, a new add-on manager, and improved privacy and crash protection among the more notable features.
For the full list of new features, check out the official feature page. Since this is a beta of version 4.0 I do recommend keeping Firefox 3.x.x installed in case any add-ons do not work.