IMHO game publishers are coming at this from the wrong angle - they should be looking at the second hand market as an opportunity rather than a threat. Over the last year or two there has been a growing trend for games to have paid-for DLC (see Guitar Hero/Rock Band as prime examples). Since this content doesn't get resold when the game does the new owner may well then re-buy the DLC.
So although yes they might miss out on the profit from the original game sale (assuming that the person who bought it second hand would otherwise have bought a new copy) they ARE still making money.
Also don't forget trade ins - many console owners I know (myself included) will trade old games for money off new ones, often allowing us to buy more NEW games then we would have done otherwise. Why not embrace this? Publishers could offer incentives if people trade in one their older games for a sequel, or a direct competitor to their game - say trading in Guitar Hero for Rock Band etc.
When the music market changed under them (i.e. the internet) the industry tried to fight the change rather than embracing it as a new opportunity, that didn't work out too well did it?