I think Marvel intentionally releases vague bits of news just to get people talking. The latest example of this is the rumor that the studio is looking at Jim Carrey and/or Adam Sandler to join the cast of Guardians of the Galaxy.
Back in November, Marvel ‘leaked’ a shortlist of actors vying for the lead, Peter Quill (Star Lord), so the two comic actors are more than likely being considered for one of the supporting roles. Also, given the membership of the Guardians, which includes a tree-man and a talking raccoon, it’s quite possible that whoever is hired would end up doing a voice-over for a CGI character.
Carrey is the better actor of the two, but he has a leading role in this summer’s Kick Ass 2, so who knows if he’d jump into another comic book movie this soon.