Sorry if this is old news but I only just heard that the VS 2010 IDE is going to be made using WPF (I also didnt know that Expression Blend was made in WPF). Apparently this should make it very easy to create your own IDE extensions and add-ins. Sounds good to me, and its also a rather comforting sign that Microsoft is very serious about WPF and is confident in its abilities.
Just wondering what other people's thoughts are on this and if you have heard anything more about the advantages that this could bring us as users of WPF and VS 2010 then please post em