Harold Ramis sent an e-mail to the Chicago Tribune over the weekend confirming the news about Ghostbusters III. In addition to offering clarification that Bill Murray would be involved, Ramis talked a bit about the overall current situation:
“yes, columbia is developing a script for GB3 with my year one writing partners, gene stupnitsky and lee eisenberg. judd apatow is co-producing year one and has made several other films for sony, so of course the studio is hoping to tap into some of the same acting talent. aykroyd, ivan reitman and i are consulting at this point, and according to dan, bill murray is willing to be involved on some level. he did record his dialogue for the new ghostbusters video game, as did danny and i, and ernie hudson. the concept is that the old ghostbusters would appear in the film in some mentor capacity. not much else to say at this point. everyone is confident a decent script can be written and i guess we’ll take it from there.
Source: Chicago Tribune