It's not Facebook's property; they just get an unlimited license to reproduce it in order to provide their service. For organizations that are not Facebook, I'm sure the situation is much more murky.
Well, no, it's Fair Use. It's a legal defense, but since a news site would be hosting their own content, and editorializing, they would be be able to claim safe harbor. So a DMCA takedown would be effectively ignores, and followed up in the courts. Regardless, it's text book fair use. http://en.wikipedia.org/wiki/Fair_use