WPF is "next-generation" and "provides a common programming model for standalone and browser applications" (Introducing Windows Presentation Foundation), that mean it can be used both for windows client and web client applications. The programming model and Xaml source files has more in common with ASP.Net development, so it seems to me does the controls. A "subset" of WPF is called Silverlight and are also Xaml web applications. See also Windows Presentation Foundation on the Web: Web Browser Applications and Deciding When To Adopt Windows Presentation Foundation - WindowsClient.net. It is also interesting that you can host WPF control in a traditional windows forms client application and forms controls in a WPF application.

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