Update: For the reasons why I struck out "almost", see the comment thread below.
is almost a good idea. People who need experiments done propose them. People who want to do experiments bid on doing the work. SE helps them find each other.
But this spoils everything: "Except for your content posted by you on the Service...you agree not to sell, license, rent, modify, distribute, copy, reproduce, transmit, publicly display, publicly perform, publish, adapt, edit or create derivative works from any Science Exchange Content...."
As far as I can tell, SE doesn't let participants agree to make their results OA. The proposer can't make OA a condition of the job, and the experimenter can't agree to the condition. If I'm right, SE should rethink and leave this decision to the participants. If I'm wrong and SE already permits OA, then it should clarify its terms of service.