It's a long in development project at the studio, and has already had some solid work done on it by Ronald D. Moore, but Deadline are reporting that Favreau will have a fresh writer for his fresh take. The basic idea, though, will remain the same: Night at the Museum not at the Museum but at a Disney theme park.
Already this is sounding like Ridley Pearson's Kingdom Keepers novels, at least as much as Pirates of the Caribbean was derived from Tim Powers' On Stranger Tides. There's also a glimmer of Kingdom Hearts in there too, and maybe Who Framed Roger Rabbit. At least, it sounds like those before we know anything at all about the film's actual plotline or lead characters.
The folklore and urban myths I know about theme parks always seem to revolve around molestation or child abduction, so I can't see any of those factoring in. Shame. I always like a little bit of folklore in these "definitive" films. Maybe they'll just about stretch to having a cryogenics lab hidden under the park someplace.
Favreau's work on Zathura seems to be the closest match in his own repertoire and that one seemed to work out fine. I'm not sure I ever want to watch it again, but it certainly wasn't an offensive piece. I'm sure he'll want to steer clear of mawkishness, and that can only be a good thing when admitting Mickey Mouse.
Now. Let's see who gets the writing gig.