Having squashed a last-minute bug found in the Mac OS X version, Mozilla has released the first preview of Firefox 3.1. Code namd "Shiretoko" after a national park on Japan's northern-most island of Hokkaido, the Alpha 1 build includes many of the features Mozilla hopes to add to the update before its final release ships in late 2008 or early 2009. These include improvements to the Smart Location Bar and better tab switching.

Pressing ctrl-tab in the Alpha 1 build switches users between current and last-viewed tabs instead of navigating through each one sequentially, similar to the alt-tab application switching in Windows (or command-tab for those of you grooving on a Mac). Users will also be able to see thumbnail previews of the pages in each tab. Surfers not wanting to get their hands dirty with an Alpha build can get this functionality now with the Ctrl-Tab extension.

Mozilla is also developing the Gecko 1.9.1 layout engine, which makes its debut in Firefox 3.1 Alpha 1. For this reason, expect sketchy compatibility when attempting to render some web pages.

If you choose to give the new build a whirl, be sure and let us know what you think below!