I'm active in our area's Startup Weekend community, and we try to stamp out the pre-fab work ahead of time. We've never had a funded project come through before, but I know we wouldn't allow it.
I'm also the organizer of a local civic hackathon, where we have one caveat: Feel free to continue work on the project you started at our last hackathon. I'm curious how many will, or how many will start from scratch.