A new contest has been announced, sponsored by Values at Play. The deadline is the first of next year; for details check the link. First prize is apparently up to eight iPhones -- one per member of your team.
Apparently you don't have to create a game especially for the contest, because there are a few games I recognize that are entrants, but your game does have to be about building a better world. (Thanks to Patrick Dugan for the news tip).