Mozilla has released Firefox 3.1 Beta 1, the first official development release of the next update to Firefox 3 just about four months after its release past June.
Firefox 3.1 is basically meant to be a completion release to get some features and enhancements that didn’t make it on time for the Firefox 3 final release. An example of this is the new tab switching behavior when pressing Ctrl + Tab (Cmd + Tab on Mac) which instead of moving to the next open tab, alternates between the current and previously viewed one. Keep Ctrl pressed while tabbing and a small dark window is overlaid with thumbnails of the most recently used tabs. You can also click on the thumbnail to select it or, press W while holding the Ctrl key to close it.