The ability to block certain users from influencing ratings at all. Many people rate movies two or three years before they are released.
Added on Apr 13 17:57
i think there are better solutions:
-can't rate movies that aren't released yet.
-rate only as a personal appreciation, movies that aren't released yet.(i mean that the rate will be visualized only by who rated)
I agree with Lazward!Some people rate an item based on magazines, trailers or personal taste and assume they're going to like/love it before even see/read it!
So, either the items are blocked to ratings before releasing or there would be two ratings (Personal Forecast Rating|Regular Rating)