Kotaku writes Sony filed a patent for a new technology that would restrict the use of game discs to one console by linking the game media to a specific machine or user account. The technique would effectively kill sales of second-hand games, but it's unknown when or if Sony plans to implement it. Gamers in the EU should be safeguarded from this though, as a EU court determined last year that consumers have the right to sell used software.
First discovered in this forum thread on NeoGAF today, Sony's technology would check a game disc's RFID tag, which is capable of remembering if that game had been linked to a different machine or account. This check is performed offline and before the game is played.
While this describes the capability to completely block a used game—or any game that had been played on another console—it's important to remember that it also can be used to simply restrict some of its features, such as online play that some publishers have subjected to one-use "online pass" codes since 2010. The system described in the patent application would obviate the need for online passes, and also end the revenue stream they generate, but the point of their existence is to drive sales of full-price retail copies, with the $10 fee serving as a kind of clawback for the time being. It also would allow for rentals to use all multiplayer features; a code supplied by the renting party could unlock all capabilities for the life of the rental; currently, some games with online pass restrictions offer free three-day trials.