Rockstar Games
It looks like Sony has hidden the ability for the PlayStation 4 to play old games in the console without telling anyone.
The recent release of "Star Wars: Battlefront" included retro games that ran smoothly, so it's technically possible for PlayStation 2 games to run on the PlayStation 4.
Wired asked Sony about possible PlayStation 2 emulation, which would mean that the PlayStation 4 could run the older games. Sony told Wired that ""We are working on utilizing PS2 emulation technology to bring PS2 games forward to the current generation, we have nothing further to comment at this point in time."
PlayStation 2 emulation could open the door to a wave of classic games coming to the new console, much like the original PlayStation games that are available for digital download right now. It's not yet clear whether original PlayStation 2 discs will work with the PlayStation 4, or whether this is only going to work for digital downloads.