Firefox 3 is in testing, with the latest build, beta 4, released Monday. Mozilla is aiming for a final release of its flagship product before the end of the first quarter of 2008. Let’s take a look at the changes coming down the pike.You can grab a copy of the latest Firefox 3 beta from mozilla.com. Linux, Windows, and Mac OS X Universal Binaries are provided in more than 40 languages. The Linux version is a bzip2-compressed tar archive. You can unpack into any location on your system.