I've updated my freely available Adobe Illustrator to WPF/XAML Export Plug-In to be compatible with the WinFX December 2005 CTP. Other than a very minor tweak to the XAML syntax, I've added Width and Height attributes to the outer Canvas tag (Chris only asked for this about three months ago). Remember that you can hold down the left shift key during export to launch the default XAML viewer; this happens to be Internet Explorer in recent builds.
Most of the feedback I get is very positive, and I continue to receive around 650 downloads of the plug-in each month. Frankly, I'm surprised that so many people have found it to be useful. If you're new to the plug-in, you might be interested in watching the 25-minute Channel 9 video I recorded awhile back. As always, comments and suggestions are highly encouraged!