Who ya gonna call? pic.twitter.com/4cvZ9p5r— Jonah Hill (@JonahHill) January 26, 2012
Although it isn't known if they plan on accepting, Jonah Hill was offered the role of Jeremy, with Emma Stone offered a character named Anna. The story has long been believed to center on a new crop of Ghostbusters trained by Dan Aykroyd, Harold Ramis, and Ernie Hudson, so it's possible that Jonah Hill and Emma Stone could play these younger recruits, or the children of these original Ghostbusters.
Bill Murray still has no plans to return to the franchise, although Dan Aykroyd revealed in May that there would still be a role for him, if he changes his mind.
Ivan Reitman is attached to direct from a screenplay that was originally written by Gene Stupnitsky and Lee Eisenberg (Year One). Etan Cohen signed on to rewrite the script last year.