It had been rumoured that the PlayStation 4 would block used games. It won't.
Speaking to Eurogamer, Worldwide Studios boss Shuhei Yoshida said, "Used games can play on PS4. That's the general expectation by consumers. They purchase physical form, they want to use it everywhere, right, So that's my expectation."
It was thought that if one system blocked used games the the other would too, however it seems Sony is staying away from this idea. So what will Microsoft do? It does seem unlikely that it would give Sony any sort of advantage, which this almost certainly would be if Microsoft to the no bused games stance.