Such a system would fail for 2 reasons; makes it difficult for the original owner to get money back when he sells his copy, and not all users have access to the net; so would that mean users without the 'net would only be able to play the game in demo mode?
Instead, a better system would be to give incentive to the original buyer; you buy the game, first registry, will give you entitlement points (maybe $5-$10 worth; afterall, for Sony, these virtual points are as good as printing money; there is no concept of inflation in such an environment). Server identifies your user id with the game id. Also, the game might include downloadable extras, such as wallpapers or a few downloadable songs, only available to the first registered user. Generally anything that fits in the theme of nice to have but are not game essential items. Even stuff like the pets from WoW CE is feasible.
You still hold the physical copy; when you sell it, the next user no longer gets the benefits of the extras, or the entitlement points. If they want to though; they can buy the extras with entitlement points, so it's not like they have no way to regain those extras.