Movieweb.com have this listed today:
Release date: July 27th, 2007
Director: David Silverman
Starring: Matt Groening, James L. Brooks, Mike Scully, Al Jean, Ian Maxtone-Graham, George Meyer, David Mirkin, Mike Reiss, Matt Selman, John Swartzwelder, Jon Vitti, Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria, Harry Shearer, Pamela Hayden, Tress MacNeille, Albert Brooks, Minnie Driver, Erin Brockovich
Read more here: http://www.movieweb.com/movies/film/13/4013/summary.php