Editor’s note: Mozilla released Firefox 3.1 beta 1 on Tuesday, October 14, 2008 at 2:42 pm PT. Check out the Mozilla Developer News announcement reposted below for more details.

Firefox 3.1 Beta 1 is now available for download. This milestone is focused on testing the core functionality provided by many new features and changes to the platform scheduled for Firefox 3.1. Ongoing planning for Firefox 3.1 can be followed at the Firefox 3.1 Planning Center, as well as in mozilla.dev.planning and on irc.mozilla.org in #shiretoko.

New features and changes in this milestone that require feedback include:

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.

More information about new web developer features are available in the Web Tech blog post.

Testers can download Firefox 3.1 Beta 1 builds for Windows, Mac OS X, and Linux in 36 different languages. Developers should also read the Firefox 3.1 for Developers article on the Mozilla Developer Center.

Note: Please do not link directly to the download site. Instead we strongly encourage you to link to this Firefox 3.1 Beta 1 milestone announcement so that everyone will know what this milestone is, what they should expect, and who should be downloading to participate in testing at this stage of development.