Also, MOST of the many people that go into making this show are TOO busy to start a large project like that. If there ever WAS a movie, it wouldn't be until after the show got cancelled.
Oh, and before you recommend "hey, how about a live action movie?", consider that most of the actors look NOTHING like their characters, so imagine a Homer Simpson with a Dennis Franz voice! And remember that most of the actors (with an exception of Yeardly Smith, who has only played Lisa, Mrs Winfield, Maggie in "Bart vs Thanksgiving" and a couple of chorus extras) play multiple characters, so it would be IMPOSSIBLE to keep all of the voices the same.
Read http://www.snpp.com/guides/movie.html for a collection of official quotes from the Simpsons staff on the movie
oh, and if you see ANYTHING about the Simpsons Movie on imdb, remember that this is the same site that once accepted a submission about the Futurama movie, starring Mr T as Fry and French Stewart as Bender!
"Nature is very un-American. Nature never hurries." -- William George Jordan