Microsoft does support hosting the silverlight plugin in a variety of different scenarios, see: http://msdn.microsoft.com/en-us/library/dd550717%28VS.95%29.aspx#using%5Fsilverlight%5Fin%5Fa%5Fbrowser%5Fcontrol

Can you explain more about your situation? Is the WPF application an XBAP, or a non browser hosted application. Would you want to publish the silverlight portion of the content on a website, or try to embed it with the application? The story is a bit trickier if you want complex communication between the silverlight content and the rest of the content being displayed and vice versa.

-Graham

Oh, Just as a warning, the WPF WebBrowser control will have airspace issues if you were comtemplating doing complex WPF layout around it: http://msdn.microsoft.com/en-us/library/aa970688.aspx

So be sure to consider whether the WebBrowser control fits into the overall layout strategy of the application before even getting into whether you can host your Silverlight content in it.

-Graham