We’ve heard on and off rumors about Microsoft and/or Sony trying to prevent the sale of used games. The latest rumor comes from Kotaku who cites a “credible insider source”. The rumor states that Microsoft will have anti used game DRM.
If true, this may would either mean the 720 will require an internet connection for gaming, or used games will be playable, but only in offline modes. As always, take every rumor with a healthy grain of salt.
While I can understand why developers want to get rid of the used games market, this is a poor course of action if it were true. Microsoft, Sony, and other developers would be better served to forge some kind of agreement with Gamestop for some cut of used game profits.