Yesterday I wrote about hardware accelerated effects in WPF 2D. Today I saw this video (http://channel9.msdn.com/Showpost.aspx?postid=403854) that show us that DirectX can be used from WPF. There are some (a lot!) differences between DirectX and WPF 3D and you might reach some point where WPF 3D isn't enough, you need the power of DirectX. Instead of a huge rewrite of WPF to DirectX, you can now combine these two and that is just soooo cool! I love it!
9 different DirectX sample apps running on a cube each. Displayed in WPF 3D!