Sony has confirmed that the PlayStation 4 won’t play PS3 games natively out-of-the-box. However the company is exploring ways to bring PS3 support eventually, which could be through a Gaikai-powered streaming service. Though according to a Sony tweet, PS3 games won’t be the only ones it will be bringing to the PS4 — PS1 and PS2 games will also be available in the near future. In the meantime, you’ll be limited to new games only at launch.
PS1, PS2 and PS3 games to be playable via the PlayStation cloud service #PlayStation2013
— PlayStation Europe (@PlayStationEU) February 20, 2013