I would have thought it would be no different to other fields, such as photography?
When a photographer is hired, unless the contract specifically states it, you get a copy of the output or end result, but the IP, copyrights and ownership belong to the photographer. As I understand it in most cases you can't even legally reproduce copies for yourself, and in fact a lot of photo processing places state this as well.
A recent good case in point for U.S. law for almost (or part of anyway) this exact issue is the case by the enterprising guy who was sued by George Lucas for making copies of the stormtroopers outfits that he designed decades ago. Google it, he ended up winning.
cheers,
Ian
It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!