Hmm... I smell a possible lawsuit?
It does appear as though some data is being taken from TWP, mainly the description and possibly other information. In any case, if they are in fact uploading maps to their site without the authors' permission I will bring this up to the rest of the staff and figure out what to do.
Well, they are, in at least one case; Lostprophetpunk's map is on there, and, considering he brought this up, I'm pretty sure it shouldn't be.
I've seen other Portal 2 Mapping Websites besides TWP. It's possible that they copy some good maps from other sites and stick them on their site.
Isn't it possible to block certain links to or from websites?
Well, if all else fails, publicly humiliate the people taking this site's maps. Maybe ask the people that posts stuff on Steam News (ex: kotaku) about doing a report about PortalDB redistributing maps. I know what they're doing is "legal", so having an story giving them bad publicity would also be "legal."
Then everyone would steal it just to get into steam news. No?
Ok that's a good idea. But if the staff does e-mail the admin, I would advise not to give them an ultimatum. By which I mean: Don't say your going to do something if they refuse or ignore the message. That might cause some issues.