I received a reply from Shapeways, and essentially, they're using various laws to absolve themselves from any responsibility, and unless the offending individual chooses to take the ship down, there's not much I can do except submit a request to have it taken down, which may or may not happen.
I made a big ass post on the page where my own ship is being sold, putting it on notice that it's theft. I contacted the guy, but I doubt I'll get a response, even if he reads it.
I know the model was converted, and since I had also released a 3DS Max 9 version on Scifi-Meshes a while ago, when their download page was still active, chances are this guy didn't have to do much, if any, converting. I know that mesh, I made every inch of it, and I know how the polys are grouped. That's definitely my model, my work, not just my design copied.
I posted about this also on my DeviantArt account, and a few of my watchers took it upon themselves to contact Shapeways on my behalf as well, something I didn't expect.
I hope no one here minded the necro post, but since I was once a part of the gaming modeling community, and because I had recognized some work on Shapeways that belongs to a few people on these forums, I knew I had no choice but to bring it to light, because I would want someone to let me know if it happened to me. Unfortunately, it did happen to me, but one of the friends I notified about it had let me know as well.
I hope those who have found their work ripped off go after the offending individuals and after Shapeways itself. Also, I read a reply that some of DJ's models were being sold on the site, so if anyone knows how to get hold of DJ, that would be a good idea.