Mozilla has just released the first beta version of its Firefox 3.1. Beta 1's new features include a new tab-switching shortcut that shows previews of the tab you’re switching to, improved control over the Smart Location Bar using special characters to restrict your search, support for new Web technologies, such as the and elements, the W3C Geolocation API, JavaScript query selectors, Web worker threads, SVG transforms and offline applications and web standards improvements in the Gecko layout engine.

However there's also support for the new HTML video and audio standards, which will "get video out of the plugin prison and let it interact with the rest of the content on pages," according to Mozilla.

Firefox 3.1 will land in final form near the end of 2008. Mozilla had originally planned to start code freeze for beta 1 in the middle of August, but decided to delay the beta release and do an additional alpha release instead.

Firefox 3.1 alpha 1 was released in July, and introduced new tab switching behavior and a new visual tab switcher with graphical thumbnails. The alpha 2 release, which was made available earlier this month, added support for the HTML 5 video element which makes it possible for the browser to natively display playable video and seamlessly intersperse it with HTML and SVG content. Therefore some of Firefox’s 3.1 features didn’t just come out of the blue.

By far the most anticipated change coming in Firefox 3.1 is the new TraceMonkey JavaScript optimization engine, which should improve the speed of Ajax-heavy web applications. TraceMonkey is still considered unstable at the moment, that’s why it has been switched off. Of course this is only the first beta, and we remain optimistic about TraceMonkey. This feature is said to boost rendering speeds up to 40 times faster than the previous version of Firefox.

If your curiosity knows no bounds, you can give it a test run. First you have to type “about:config” into the address bar. Then type “javascript.options.jit.content” into the “Filter” field that pops up, and double-click it to set it to “True.” Restart the program and your speed booster will be on.

Another new addition to the first beta is the Geolocation feature that allows the browser to indicate your location. "The Geolocation API in Firefox 3.1 exposes a single API to web developers, but can potentially be backed by a number of different location sources," the developer notes claim.

In beta 1, this functionality is built on top of the Loki web service, which is supplied by Skyhook and determines the user's position by comparing local WiFi access points with information in its global reference database.

Firefox had 19.46% of the recorded usage share of web browsers as of September 2008, making it the second-most popular browser in current use worldwide, after Internet Explorer. Firefox runs on various versions of Microsoft Windows, Mac OS X, Linux, and many other Unix-like operating systems