Mozilla has released Firefox 3.1 Beta 2 for testing. Firefox 3.1 Beta 2 includes the following new features:

• Available in 54 languages
• Private Browsing Mode
• Easier clearing of recent history
• Support for web worker threads
• New TraceMonkey JavaScript engine
• Improvements to the Gecko layout engine
• Removed the new tab-switching behavior due to user feedback
• Supports and elements, W3C Geolocation API, JavaScript query selectors, CSS 2.1 and 3 properties, SVG transforms and offline applications.

You can download Firefox 3.1 Beta 2 here, but be sure to read the Known Issues & FAQ’s first.