The guys over at Xceed, makers of the powerful yet free Xceed DataGrid for WPF have just launched the WPFwiki. The wiki was created to be a community resource for developers working with Windows Presentation Foundation. Even though the site was just launched, the idea started 
in 2003 when the WPF DataGrid was just starting to be developed. As the developers encountered problems and questions that they felt would be of common interest, it was recorded in a database along with the answer. In March 2007, the WPF FAQ on WPFwiki.com was created and over 100 initial questions and answers were published, in Wiki form, for the benefit of developers working with WPF.
In addition to a large WPF FAQ, WPFwiki is also a great place to find WPF related resources. From books to blogs and even some college classes, if it relates to WPF and is good, chances are it will be listed.
To help make sure the contributions to the WPF FAQ keep coming in and are of good quality, Xceed is planning to award prizes to the top contributors a couple of times a year. The prizes include product licenses, iPods, and more.