WinRT is a replacement for the Winapi. The api is native, very unlike WPF that runs as a layer on top of the CLR. It certainly resembles WPF, part of what causes confusion. It adopted the metadata format of managed code, replacing type libraries of old. And uses XAML for UI designs, much like WPF, Silverlight and Windows Phone. You can still write WPF apps for Windows 8 but your app can’t be published through the store, won’t integrate with the Metro desktop nor will it run on tablets that are based on the ARM core. Whether that’s a real problem depends a great deal on how well Metro will do in the market place.