Creative Commons, the Free Software Foundation, and OpenGameArt, three organizations naturally concerned with the free transmission of culture, are partnering to make the world a better place for free game development. The contest is taking place in two phases: first, participants are encouraged to create new game art usable by anyone (as long as they attribute the source), and upload it to OpenGameArt.
Then, all that art will be used to make games, between July 1st and July 31st. Prizes will be awarded for standouts in both categories. It seems pretty likely you'll be able to download and play all the games from the contest as well, given that, you know, "free software" business. If you don't want to participate artistically, you can do so financially, by donating to the style guide artists and prize fund. Consider it an act of ironic charity.