Well not Halloween per se, but when does Disney start decorating the parks?

I'm heading down September 2-8. I've never seen holiday theming before at Disney, so it could be something fun. If it's even done during my trip.

Do they still touch up Haunted Mansion? I'm going with someone who's never been, so I hope nothing is "out of place" like pumpkins in every ride. Then again I could be way off.