Microsoft revamps the Windows 8 interface with touch in mind, borrows heavily from WP7

We were more interested in the tablet user interface of Windows 8, but it turned out that there really won't be much distinction, because the new Live tile-based interface in the Metro UI style of Windows Phone 7 will seemingly be as standard for server PCs, as for the smallest slate.
• Fast launching of apps from a tile-based Start screen, which replaces the Windows Start menu with a customizable, scalable full-screen view of apps.
• Live tiles with notifications, showing always up-to-date information from your apps.
• Fluid, natural switching between running apps.
• Convenient ability to snap and resize an app to the side of the screen, so you can really multitask using the capabilities of Windows.
• Web-connected and Web-powered apps built using HTML5 and JavaScript that have access to the full power of the PC.
• Fully touch-optimized browsing, with all the power of hardware-accelerated Internet Explorer 10.
With that out of the way, Windows 8 will be the biggest revamp since Win 95: "The user interface and new apps will work with or without a keyboard and mouse on a broad range of screen sizes and pixel densities, from small slates to laptops, desktops, all-in-ones, and even classroom-sized displays.", says Microsoft. With that said, Redmond is placing restrictions on the type of hardware to run the new operating system. Since touch will be deeply integrated now, not a layer, there are some requirements towards touchscreens - at minimum they should have 1024x768 pixels of resolution, with the best starting point being 1366x768.
Redmond also noted the instant-on feature, which hibernates the operating system immediately and then seamlessly fires it back up, just as we would expect on a tablet. Cold boot should take about six seconds with SSD. Upon installing, Windows 8 recognizes the underlying hardware, and scale accordingly, including that Live tile-based, adjustable interface. Have a look at what's in store with Windows 8 in the video below.
source: Microsoft (interface & hardware)