The next browser company to jump into the Phone OS market. And it looks a lot like Windows 8/Windows Phone 8:
New images revealing the latest state of Firefox OS have hit the Web a week after shots showing an outdated version of the Mozilla mobile operating system first emerged.

The new shots show an operating system that has significantly changed from the version we first saw. Firefox OS no longer looks like a mix of iOS and Android and seems to have found its own identity.

The most significant change is in Firefox OS's home screen. Previously, the screen showed a grid of icons laid out very similarly to iOS's apps. Now, the screen shows fewer apps and displays them in rectangular-shaped icons -- which calls to mind Windows Phone's Live Tiles, although they are significantly different.
That from the LA Times. and if you'd want to check it out first hand:

What better way to learn about Mozilla's new mobile operating system than to get some hands-on experience with it?

While you can't run the Firefox OS on a smartphone yet, Mozilla will let you run it on a computer desktop.

The operating system's engineering team announced this week that they will begin posting nightly desktop builds of Firefox OS online for anyone to play with.

Desktop builds of the OS, codenamed Boot2Gecko (B2G), will be offered for all major PC platforms -- OS X, Windows and Linux. The builds are limited to a desktop and can't be sent to a phone or tablet, the Firefox OS team cautions.
From http://www.pcworld.com/article/25956...r_desktop.html.

And in case you are any bit interested in seeing it first hand, here's the links to the nightly build pages:

The main page of information and links

The actual Mozilla nightly builds