Version 3.1, codenamed Shiretoko is planned to include support for the <video> and <audio> tags as defined in the HTML 5 specification. Cross-site XMLHttpRequests (XHR), which would allow for more powerful web applications and an easier way to implement mashups, is also in planning. Native JSON DOM binding, a powerful feature for web developers, may also be included, together with full CSS 3 selector support. Firefox 3.1 will use the Gecko 1.9.1 engine, which includes a few features that were not included in the 3.0 release.
Version 3.1 Alpha 1 was released in late July 2008. Version 3.1 Alpha 2 was launched on September 6, 2008, adding new video support and enhancing the speed of some JavaScript computations. Code named "Shiretoko," Mozilla said it will be the last in a short series of alpha editions, and timely released just days after Google introduced competing Chrome software Google Chrome. Google Chrome is only available for Windows XP and Vista as of now.
Free Download: Click To Download Mozilla Firefox (Shiretoko) for Windows 3.1 Alpha 2