"We're very excited to announce the official release of Firefox 3.5! You can download Firefox 3.5 at firefox.com and enjoy the new features and faster performance. If you're using the latest version of Firefox 3.0, you can get Firefox 3.5 by clicking on the Help menu and then selecting Check for Updates.
* Firefox 3.5 is available in more than 70 languages – get your local version.
* We have included tools for controlling your private data, including a Private Browsing Mode, and the ability to go back in time and Clear Recent History.
* Firefox 3.5 has support for the HTML5 <video> and <audio> elements including native support for Ogg Theora encoded video and Vorbis encoded audio.
* Users can enjoy Location Aware Browsing using web standards for geolocation.
* Web developers can make use of native JSON parsing, and web worker threads.
* This release includes improvements to the Gecko layout engine, including speculative parsing for faster content rendering.
Here is a video about what's new in Firefox 3.5: