I noticed when I went to one of the libraries I work with that they had received their public performance rights to show movies at the library, apparently as some blanket deal from the Department of Libraries. I read the documentation that came from Movie Licensing USA, an outfit that provides public performance licensing to schools and libraries. With a cost that they never state but call “reasonable” this group will give you a piece of paper that seems to say that the MPAA will stay off your back if you want to show movies @ your library. Well, not all movies, just ones by the major studios that they represent. You also can’t advertise the showing of your movie to the general public. If you want to put a listing in the newspaper you can only do so in the vaguest of terms — without actually using the name of the movie you are showing. They suggest ideas like “The library will be showing a tale of wizardry by the author JK Rowling.”
While the company won’t give you information about copyright law in general — ALA has this page for the curious — they seem more than happy to tell you what you are NOT allowed to do under copyright law. The printed materials that come with the license are even more bizarre and talk about “avoiding the embarassment of a lawsuit” as one reason a library might want to obtain public performance rights.
If your library is looking into obtaining public performance rights, the Wisconsin Department of Public Instruction has a good list of questions to ask a licensing service.