My wife and I submitted a proposal for an Innocentive challenge sponsored by the local science museum a while back. The task was to design the next great traveling exhibit for science museums, and we had fun writing our proposal. A few months later we received an email announcing the names of the winning teams, and that's all - no details on the winning proposals, no feedback on our submission. I understand that they can't give everyone customized feedback, but I was still left feeling like I got absolutely nothing from the experience - I have no idea what parts of my proposal needed improvement, no idea how to make my next proposal better. For a different kind of challenge (say I found a successful way to "convert lactic acid to acrylic acid" but my solution still wasn't chosen), I'd probably be angry about the lack of transparency. So yeah, that was probably the first and last time I'll try to solve one of their challenges.