Sony has applied for a patent on a hardware-based DRM technology that would let the company block second-hand games. Filed last September, the application (PDF) hadn't been published until this week and it's unclear if or when the patent will be awarded. The document outlines an "electronic content processing system, electronic content processing method, package of electronic content, and use permission apparatus" that "reliably restricts the use of electronic content dealt in the second-hand markets."
To accomplish that, Sony would outfit its retail game discs with radiofrequency tags and programmable memory chips. When inserted into a system, the disc would wirelessly collect unique information about the console. If someone attempted to play it on a different machine, the identifying data stored on the disc wouldn't line up and some form of block would be imposed, though the details are slim here.
Patent - http://www.freepatentsonline.com/20130007892.pdf
Source - Sony applies for RFID DRM patent that would block used games - TechSpot
This would be a terrible move if something of this sort is implemented in the upcoming eighth-gen consoles!