Ghostbusters 3?

Has there been any mention of a 3rd Ghostbusters movie coming out? You know how "Retro" is really "in" right now for movies, music and video games, as we have seen with Teenage Mutant Ninja Turtles or TMNT (2007), Batman Begins, Indiana Jones, Rocky Balboa and many others? So is there any possibility of a movie called "Ghostbusters 3", or "Ghostbusters Return", or "Ghostbusters Reunite"? Anyone know of some details or reliable sources, or simply rumors about such a movie being produced or released? Tell me the lot!