“It,” a horror film launching Sept. 8 about young boys in a fictional Maine town who face up against a creepy, child-killing clown-entity named Pennywise, is expected to be one of the highest grossing movies of the year.I thought it was already a movie? Tim Curry played the clown? John Ritter, Richard Thomas had roles?... Or was that a different movie with a clown in the storm sewer?