Aaron Sorkin, creator and exec producer of The West Wing, announced Thursday that he will be stepping down at the end of this season. "This has been the experience of any writer's dreams," Sorkin says. "I had the best job in show business for four years and I'll never forget that." Fellow exec producer/director Tommy Schlamme will also be leaving. In a statement, NBC thanked the two for helping create "one of the finest shows to ever air on television," and added that exec producer John Wells has agreed to "assume a more active role next season."