Good question. I actually just went through this on a transaction. First, I would recommend reading the purchase contract carefully to ensure it does not mention anything about wall holes. (Each state and region can vary). If you have the time, and want the buyers to be pleased when the do a walk through your home the day before closing, it is a very nice gesture (although you're not obligated to) patch the holes and re-paint over them. As you can imagine, it is very unlikely that their wall hangings will be the same size as yours, or that they'll even want to hang their decorations in the same places you had yours. I would not worry about small, tack size holes, but I'm sure the buyers would be very appreciative if you took care of the larger ones.
Good luck and congratulations!
Licensed Real Estate Associate Broker
6129 State Rt. 8 Chestertown, NY 12817