The beta was made available for Windows, Mac OS X and Linux in 36 different languages.

According to the developers, the list of improvements for Firefox 3.1 Beta 1 includes the following:

– Web standards improvements in the Gecko layout engine
– Added support for CSS 2.1 and CSS 3 properties
– 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 <video> and <audio> elements, the W3C
– Geolocation API, JavaScript query selectors, web worker threads, SVG transforms and offline applications.

However, what the new version does not feature is the TraceMonkey JavaScript engine. Previously, Mozilla promised that the engine would improve JavaScript speed by a factor of 40, but the development process seems to have gone anyhow but right.

These being the fact, all hopes are now moved to late November, when the second beta is scheduled to arrive.

Firefox 3.1 Beta 1 is available here for download.