My understanding is that LJ owns the copyright for the layouts for this contest. The thing is with contests you frequently cede ownership of copyright at the time of submission, not when it's incorporated. So they may own all of these submissions. You would need to look at the actual submission form/paperwork to see. My only concern with stealing these from LJ, just like hacking the styles LJ implemented, is that if it violates LJ's copyright, the user's put squeaky in the middle. As the owner of the site, he'd be the one dealing with DCMA claims from the Evil Empire. I don't want to screw IJ in the process of screwing LJ. I want to put that out there because I don't think people realize it.
I think a contest is a fabulous idea, maybe through a community like nameless_layout?