I'm participating in IntroComp: http://introcomp.org/
Currently putting the finishing touches on the game I'll be submitting, which will of course be a free software and free culture work: Licensed under the GNU Affero General Public License (AGPL) version 3 (or any later version.)
There are some rules to follow ("Authors must refrain from discussing any entries in a public forum during the voting period") so that's all I think I can say for now.