Mozilla has released the first release candidate of Firefox 3.6, you can download it over here. Here's the changelgo:
Firefox 3.6 Release Candidate is built on Mozilla's Gecko 1.9.2 web rendering platform, which has been under development for several months and contains many improvements for web developers, Add-on developers and users. This version is also faster and more responsive than previous versions, and has been optimized to run on small device operating systems such as Windows CE and Maemo.
* Made some changes to how we allow third party software to integrate with Firefox in order to prevent crashes.
* This release candidate is available in more than 70 languages - get your local version.
* More than 70 fixes from the last beta to improve performance, stability, security and features.
* The ability to run scripts asynchronously to speed up page load times.
* 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* Firefox 3.6 will alert users about out of date plugins to keep them safe.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.
* Support for new CSS, DOM and HTML5 web technologies.