I think certain fanfics would be better suited for movies than others. Some people take the creative freedom of fanfics a bit too far and in a sense ignore the source content. I'm not entirely sure if my Revenge series would be good for a movie, but heck it would be awesome if a movie were made based off of it, even if it were fan made. Then again, any fanfic could be made into a fanmade movie, in which case the quality of the story would not matter pertaining to the overall quality of the resulting movie.