Firefox 4 Beta 4 is now available for Windows, Mac OS X and Linux. There will be one final beta version in September, before Mozilla signs off on Firefox 4 which is scheduled to arrive in October. This version includes "Tab Groups" which has been renamed from Tab Candy, it allows you to group specific tabs into groups, for example: work, fun and anything else you could think of. The feature can now be accessed with the keyboard shortcut Ctrl-Space. Direct2D rendering is still not activated by default. The release notes can be found here.