With the latest development milestone of Firefox 3.6 available for download and served to all currently Beta program participants, Mozilla should now be on track to graduate the browser to the next testing Build, namely Release Candidate. Hitting RC would mean that Firefox 3.6 is in near final form, and in fact only weeks away from finalization, with the general availability deadline initially planned by the end of 2009.

Despite having set up to offer a single Beta of Firefox 3.6, with the evolution to RC planned to happen in Beta revisions steps, Mozilla ended up transforming Beta revisions into fully fledged Beta. As of earlier this week, the company is up to Firefox 3.6 Beta 4, a release which will be served as an automatic update to the half a million Beta testers currently running version 3.6.

“Mozilla community released Firefox 3.6 Beta 4, and issued an update for all Firefox 3.6 beta users. This update contains over 100 fixes from the last Firefox 3.6 beta, containing many improvements for web developers, Add-on developers, and users. Almost 70% of the thousands of Firefox Add-ons have now been upgraded by their authors to be compatible with Firefox 3.6 Beta. If your favorite Add-on isn’t yet compatible, you can also download and install the Add-on Compatibility Reporter from addons.mozilla.org – your favorite Add-on author will appreciate it,” revealed Mike Beltzner, director of Firefox.

According to Mozilla, another 100,000 to 250,000 testers are needed in order to provide feedback on the pre-release version of Firefox 3.6. “The Mozilla community appreciates your feedback and assistance in testing this preview of the next version of Firefox. Your beta software will update itself periodically, and eventually will be updated to the final release itself,” Beltzner added.

As Firefox 3.6 is getting closer to RC, users should no longer expect any new additions to the browser. Mozilla is currently pushing ahead with the development process in an effort to ship Firefox 3.6 in December 2009. This could theoretically still be possible, despite the fact that the RC has been also delayed to December 2009.

According to Beltzner, the Beta of Firefox 3.6 / Gecko 1.9.2 introduces several new features for users to evaluate:
- (New in this version) Support for the HTML5 File API
- The ability to run scripts asynchronously to speed up page load times.
- A mechanism to prevent incompatible software from crashing Firefox.
- Users can now change their browser’s appearance with a single click, with built in support for Personas.
- Firefox 3.6 will alert users about out of date plugins to keep them safe.
- Open, native video can now be displayed full screen, and supports poster frames.
- Support for the WOFF font format.
- Improved JavaScript performance, overall browser responsiveness and startup time.
- Support for new CSS, DOM and HTML5 web technologies.”

Firefox 3.6 Beta 4 for Windows is available for download here.
Firefox 3.6 Beta 4 for Mac OS X is available for download here.
Firefox 3.6 Beta 4 for Linux is available for download here.