I’ve been in talks with Leadwerks, who make 3D World Studio and they seem very interested in getting into the XNA domain.
They have started up a forum for XNA users to post to for help or info.
Joshua Klint, who I was chatting with has also posted on the XNA forums as well in the Artists Corner
Hopefully a lot of good could come from this, maybe another XNA partnership who knows!
Also Johnnylightbulb is close to finishing his content processor for 3D World Studio files, so you can use the proprietary format instead of exporting everything to .X.
A little snippet of what is possible with the Mapping engine, hmmm