Windows 8 has an entirely new interface called Metro, although the old desktop is one click away. Metro applications will be available through the brand new Windows Store. The linked story has some screenshots and details; the link in that paragraph goes straight to a longer article from Microsoft.
One of Windows 8’s biggest new features, compared to previous versions of Microsoft’s PC operating system, is the Windows Store section. The app download store will be part of the beta test of Windows 8 when it launches sometime in late February. In the newest post on the official Microsoft Store developer’s blog, Microsoft’s Jonathan Wang describes how the team is designing the Windows Store user interface to work well for its users.