Dan Aykroyd let go the Ghostbuster news while being interviewed by The Boston Globe that "Script is commenced early summer. Hope to be in production by late fall 2009"
This does not mean that the film has a green light yet. The script is currently being written by the guys who write for "The Office". Once that is finished then off course the casting news will start being made public. I have heard that the direction of this film is going the way of a pass the torch scenario. If done right that would be cool. Bill Murray, Dan Aykroyd, Harold Ramis and Earnie Hudson are getting a bit to old to be out there fighting other worldly demons (AKA: Ghosts). Although I'm happy that writers want to see the original Ghost Busters on board to take on some poltergeist baddies, a new team to take their place is only natural if you are to continue the Ghostbuster's franchise. My picks for the new team are: Vince Vaughn, Jack Black or Seth Rogan (but not both), Chris Rock or Chris Tucker (again not both, one or the other) and for Egon I think Robert Downey Jr. would fill the role's shoe's just fine.
Sigourney Weaver has yet to confirm or deny weather or not she will be involved in the film. Either way I'm looking forward to seeing the next addition to this once blockbuster franchise.