Perhaps the star feature of this version is the new Private Browsing mode, which has become widely popular under its “Porn mode” nickname. Basically, this mode will allow the user to leave no local traces of his or her online activities.

Mozilla has tried to wipe off the “Porn” tag by claiming that the mode is the best choice for online holiday shopping, among other things.

Additional features in the Firefox 3.1 Beta 2:

– New functions that make it easy to remove the history of your past few hours of browsing, or remove all traces of a website.
– New support for web worker threads.
– The new TraceMonkey JavaScript engine is now on by default for web content.
– Improvements to the Gecko layout engine, including speculative parsing for faster content rendering.
– Removed the new tab-switching & preview behavior based on feedback from Beta 1 users
– 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 2 is available here.