Mozilla originally showed off its Metro style Firefox browser for Windows 8 back in October, but the company has started to distribute it in the latest nightly builds this week. Like Chrome, with Firefox for Windows 8 you'll need to set the browser as the default one to access the "Metro style" version. This allows Firefox to run in Microsoft's new Windows 8 environment.
We tried it out on Windows 8 this week, and it's clear the version available is in the very early stages of release. Tabs are functional, alongside the ability to pin and favorite sites, but the settings are somewhat limited. We found that if you use the Windows 8 search Charm within Firefox it will, oddly enough, use Microsoft's Bing search engine rather than Google — despite that being the default in Firefox.
Mozilla appears to be building its sync options into Firefox Metro style too, with options to control passwords and do not track data. Overall it's a fairly basic implementation right now, much like Google's Chrome Metro style version. Mozilla has, however, chosen to implement Windows 8's app bar option, allowing you to swipe from the bottom or top to control tabs, downloads, and other options. The Metro style version is available now in the nightly builds, but after a few hours of use we noticed it stopped launching so be mindful of the early bugs if you're interested in testing.