Sony has been working on new technology for limiting used game sales, and has applied for a patent. The patent was filed 09/12/2012 by SCEJ.
Perhaps this work is where the rumour came from. Or perhaps it independently corroborates the rumour.
Anyway, here's some of the relevant detail:
According to the present embodiment, realized is the electronic content processing system that reliably restricts the use of electronic content dealt in the second-hand markets. As a result, the dealing of electronic content in the second-hand markets is suppressed, which in turn supports the redistribution of part of proceeds from sales of the electronic content to the developers. Though in the following description a game application (AP) is exemplified as the electronic content, the present embodiment is similarly applicable to various kinds of electronic content such as an office suite, images, and music content.
It works by supplying a contactless RF tag with each copy of a game (NFC?), which can (independent of a network connection), remember if a game has been tied to a different machine or user account previously. The system checks with the tag before playing the game.
By employing the game playing system 1000 according to the present embodiment, the use permission tag 220 together with the game disk 210 is supplied to the user, and the use permission tag 220 actively determines the use permit/rejection of electronic content. Thereby, the use of game AP stored in the game disk 210 can be restricted as appropriate according to the attribute of a reproduction device. Consider, for example, a case where used is a game package 200 distributed in the second-hand market. Then the ID of reproduction device for the game disk 210 differs from the legitimate use device ID stored in the use permission tag 220, so that the game disk can be reproduced in a mode which is predetermined for those bought and sold in the second-hand market. Also, for example, a content key may be supplied to the reproduction device 130 and the encrypted game AP may be decrypted using the content key only if the reproduction device ID matches a legitimate use device ID. Hence, use of game APs bought and sold in the second-hand market can be eliminated.
I suppose I should say that this doesn't mean PS4 will, for sure, restrict second hand games. This would not be the first time Sony registered patents in this area and then did nothing with the tech. In fact I remember a patent fueling rumours prior to PS3's launch. The decision would be a business one, not one based on technical feasibility. This system would be relatively expensive to implement vs network-DRM. Although it could have the double effect of limiting piracy - at least until pirates could hack or reproduce the 'rf tag' system.
The last official comment we had from someone at Sony was Jack Tretton's "'for the record, I'm totally opposed to blocking used games." - but maybe people would be better reassured by a comment from SCEJ...
So with those qualifications out of the way, have at it :P
edit - since it's causing some confusion, the application refers to a system that can tie a game to your user ID (i.e. your account), or a machine ID via the RF tag. For people wondering what would happen if your console died etc.