Thanks!WARNING on the contest rules:
"By submitting your story, you accept all contest rules and agree to be bound by the decisions of the judges, which will be final. You also agree that if you are a Grand Prize or First Runner-Up Winner, your story becomes the sole property of General Mills, and General Mills reserves the right to edit, adapt, copyright, publish, transfer and use all or a part of your entry without further compensation."
It sounds like they wouldn't even have to put your name on it if they didn't want to, because you're selling every ounce of the copyright.
The following seemed a little weird too, though probably not as bad as the first blurb:
"Except where prohibited by law, each winner will be required to sign a release giving General Mills, the book publisher and their respective advertising and promotion agencies full rights to use the winner’s name, likeness, image and voice for Contest related advertising and publicity, including such usage on the Internet."
It sounds like they could use your likeness/voice/name in any way they want without consulting you: I would at least like to be in the loop for something like that.
Also, you do have to be a US resident.