Mozilla team has just released Firefox 4 beta 8 bringing new features:
-the Firefox Sync setup experience has been greatly improved across desktop and mobile devices
-additional polish for the Add-ons manager
-speed, functionality and compatibility improvements to WebGl (WebGL is a context of the canvas HTML element that provides a 3D graphics API implemented in a web browser without the use of plug-ins)
If you, for instance, want to use the bodybrowser from Google you need WebGl activated (Chrome/ium 8, Opera 11, Firefox 3.6 don't have WebGl capabilities).
How do we activate WebGl?
type about:config into the address bar, search webgl and double-click on webgl.enabled_for_all_sites to make it TRUE.
Download Mozilla Firefox 4 beta 8 from here
For launching, extract the archive, open the firefox folder and double-click the firefox executable (this works great even if you have firefox 3.6 installed, if you don't like this beta, close it and launch the regular 3.6 version from Applications/Internet).