Silverlight is here

Microsoft has released a plug-in for delivering next generation media experiences and rich interactive applications for web. This is a cross-browser, cross-platform plug-in which facilities the WPFs' rich look and feel.
Silverlight was formerly known as WPF/E.
Besides me telling you about Silverlight go to Microsoft and see for your self, you also can find some nice samples done.

http://www.microsoft.com/silverlight

NetAdvantage for WPF

Infragistics have released a beta control set which is to be used for WPF (,.NET 3.0) named NetAdvantage for WPF. I think there they have created some cool control set which we'll be able to use with our development. If you are interested find more information at http://www.infragistics.com/hot/wpf.aspx#NetAdvantageforWPFBeta .