In spite of any official Windows 8 word, it has been rumored for a while now that Microsoft will be offering two different interfaces with Windows 8. One, allegedly, will be a tiled interface (similar to the tiled Metro/Windows Phone UI). This interface is believed to be MoSH (Modern Shell). Supposedly, this will be the primary (if not sole) interface for Windows 8 tablets and slates. The second interface will be more of a classic Windows Shell and will be the UI for Windows 8 desktops and non-touch-centric Windows PCs.
Source...