In my previous XAML-related post, Mike asked about my conversion from SVG to XAML. I know of two such programs that help with this (and I see Will also listed them in a comment):
I actually couldn't use either of these in my case, since I originally created the playing cards to be compatible with the next Avalon CTP then backported them to the March CTP.
As for 3D XAML, I know of:
I'm sure we'll be seeing a lot more tool support for XAML in the near future, but is anyone aware of other helpful tools out there?