While some solid changes to JavaScript rendering and other under-the-hood code have landed in the latest Firefox developer's build, the bulk of what's new focuses on the second version of the recently introduced Android version of Aurora. Aurora 9 for Android includes some big interface changes designed to improve its usability on tablets, support for native camera apps, faster start-up times, and broader language support.

Firefox 9 Aurora for Android debuts a new way to interact with tabs, and ports the browser's signature bigger Back button to the mobile operating system. (Credit: Mozilla)

Firefox 9 Aurora can be downloaded for Windows, Mac, and Linux, and Android.

Firefox 9 Aurora for Android debuts some sweeping interface improvements. The Back button is now attached to the location bar, so it looks similar to the desktop Firefox. The location bar has been stretched so that the Refresh and Bookmark buttons are farther to the right and easier to reach on tablets. It puts Synced activity closer at hand, too. Mozilla anticipates this change will make it easier to use the browser on devices with larger screens, specifically tablets.

Tab implementation has been changed, too. You can swipe and hide the tab bar without being forced to show the tab thumbnail preview. The bar itself can be completely hidden, too, for full-screen viewing. This shows up best in portrait mode, where tabs appear in a list on the top left and keep them out of the way until needed.

Along with native camera app integration into the browser, developers will have an easier time validating certain types of input via new support for HTML5 automatic input validation. This feature makes validating certain types of input much simpler for developers.

The changes that have been announced so far for the desktop versions of Firefox 9 Aurora are largely invisible, unless you've got a penchant for cracking open the browser and reading through miles of programming. There's a new JavaScript engine optimization called Type Inference that makes the browser faster on benchmarks like Kraken and V8, although Mozilla didn't say how much faster. JavaScript can also be used to detect a browser's Do Not Track preference, the option that tells Web sites not to use cookies to track a person's browsing behavior. Mac users on OS X 10.7 Lion finally get two-finger swipe, improved multi-monitor support, and updated icon and toolbar styles designed to fit in with the operating system's changes.

Changes made to Firefox 9 Aurora can be read here.