Mozilla has rolled out Firefox 3.6 RC1 (Release Candidate Pack 1), following are the latest features which they are testing on the beta build.
You can expect less browser crashes in the stable version of Firefox 3.6 because the developers are changing the way how the third party extensions (softwares) is integrated into Firefox. The release candidate is available in more than 70 languages, so you can get your own local language copy to test it.
70+ bugs have been fixed to improve performance, stability, security and features
Ability to run scripts asynchronously to speed up page load times
Browser appearance can be changed by a single click with the inbuilt support for Personas
Automated alert system to display outdated plugins
Full screen video support added for Open and Naive video, also supports poster frames
New CSS, DOM and HTML5 support have been added
Lets wait for the stable release for some kick ass features, meanwhile if you are eager to checkout the beta version, you can download and test Firefox 3.6 RC1 from http://www.mozilla.com/en-US/firefox/all-rc.html