Actually, I think Sony might be able to Fox but they couldn't touch Marvel because, at the end of the day, Spiderman still belongs to Marvel. I mean, if Marvel uses Spiderman's likeness to promote Spiderman comics, is Sony going to even get upset let alone have grounds to sue?
I read somewhere that Fox could, presumably, use the Daily Bugle as an Easter egg in Daredevil or Spiderman if it wanted to but, because Fox is owned by Newscorp, they would rather take the opportunity to promote one of their own, real life newspapers. On the other hand, the Kingpin can't appear in a Spiderman sequel, at least not as the main villain because Fox, presumably, still owns the rights to use the Kingpin, presumably for use in a Daredevil sequel.
It isn't really clear what Fox and Sony could get away with in terms of using 'each other's' characters but it is clear that Marvel has to be careful not to license a character to more than one company or else risk pissing everybody off in the process.
