In addition to all the goodies that DVD contains, they have also inconspicuously slipped in a preview of The Simpsons Movie as one of the bonus features!
Sadly, the X-3: X-Men - The Last Stand DVD isn't going to be out until October 3, but we have a summary of The Simpsons Movie preview:
Starting out in color and then given to us in black and white animatic form (Homer even explains that the film will look a lot better), we see him driving a pack of dogs through a snowy terrain. He is whipping them and yelling, switching arms so he can continue whipping them and eventually Homer gets attacked by the very dogs who are helping him. Aside from this being done in almost stick-like animation, the feeling and vibe of The Simpsons Movie (and the show) comes through.