Mozilla has released the first beta of Firefox 3.1 which is, as the version number implies, a not-so-big new release.

The final release is scheduled for the first quarter of next year, so only a few months are left and most of the changes we see today are what we'll see then, except for one major part: privacy browsing. Due to the popularity of the privacy browsing feature - which is available in Internet Explorer 8, Safari 3 and Chrome - Mozilla decided to add this unplanned feature in 3.1, but it hasn't materialized yet.

So what is included in this release? The Gecko engine received updates to improve support for web standards, as well as support for CSS 2.1 and CSS 3 properties. Concerning cutting edge videos, Firefox 3.1 now supports the <video> and <audio> elements (also shown in Opera Labs builds), as well as the W3C Geolocation API, JavaScript query selectors, web worker threads, SVG transforms and offline applications.

In the areas of tabbed browsing their is now a new tab-switching shortcut that shows thumbnails of the tab you’re switching to (which is also available in Opera through the preferences). Similar to Internet Explorer and Chrome, Firefox 3.1 shows the tab bar even when only one tab is open. It also has a new "+" button to add tabs, though it's not placed next to the tabs, but at the end of the tab bar.

You might be thinking, hey, where's TraceMonkey? Well, it's in there, but not yet enabled by default. The plan remains to get it finished before final release, but you can manually set javascript.options.jit.content in about:config to true and restart the browser.

You can try this new release, but be sure that some bugs may arise and extensions be broken.