Presumably this means that we could expect to see the movie coming out for the summer of 2010: twenty-six years after the original Ghostbusters premiered in 1984 and over twenty since 1989's Ghostbusters II.
Incidentally, Ghostbusters: The Video Game was supposed to be out in time for the 2008 holiday season, but corporate takeover politics has pushed it back to possibly 2009 and the quarter-century anniversary of the first movie. The Ghostbusters game features a script written by Ackroyd and Ramis, and features all four of the core Ghostbusters actors lending their voices (in addition to William Atherton and Annie Potts coming back).
I'll be keeping my eye on this new film project, 'cuz in over ten years of speculation this is the closest I've seen it becoming a reality. There was a third Ghostbusters movie being planned as far back as 1996, which would have had the Ghostbusters dealing with Hell itself and have Chris Farley playing a new team member. The first movie has held up amazingly well over the years (and Ghostbusters II seems to be more appreciated today than it was on its first release). If done right, Ghostbusters III will make for a terrifically fun transition for the franchise into the modern era.
(I just hope that Rick Moranis is up for returning...)