Adrew Griffiths and a friend of him were asked to write the software for an interactive VJ editing system for the Ford stand at the Geneva motorshow. And guess what? Yes, you're right! They decided to use XNA for the implementation.
Not a believer, ugh? Then just watch the following video and be prepared to get spellbound:
What did I tell you? So now you're interested ... well, you can find more info about the project here.