Firefox 3.1 Beta 3 is a public preview release intended for developer testing and community feedback. It includes many new features as well as improvements to performance, web compatibility, and speed. We recommend that you read the release notes and known issues before installing this beta,” reads the Mozilla Developers Blog.

The new release packs together the following features:

– Improved the new Private Browsing Mode, including the ability to “Forget This Site” from the History sidebar.
– Improved performance and stability with the new TraceMonkey JavaScript engine.
– Improvements to web worker thread support.
– New native JSON support.
– Improvements to the Gecko layout engine, including speculative parsing for faster content rendering.
– Support for new web technologies such as the <video> and <audio> elements, the W3C Geolocation API, JavaScript query selectors, CSS 2.1 and 3 properties, SVG transforms and offline applications.

Firefox 3.1 Beta 3 is available for download for Windows, Mac OS X, and Linux in 64 different languages.