WPF Datagrid
Microsoft has released a WPF Datagrid. What's interesting is that both binaries and source code are available on Codeplex.
Jaime Rodriguez has 3 blog posts on the topic:
http://blogs.gotdotnet.com/jaimer/archive/2008/08/13/dabbling-around-the-new-wpf-datagrid-part-1.aspx