PS1, PS2, PS3 games on PS4
Backwards compatibility of some kind has always been a feature of PlayStation platforms since the PS2. The PS2 could play PS1 games and for a solid chunk of time the PS3 could play both PS2 and PS1 games. The PS4 is set to have that, too, but this time around it'll be cloud-based, where gamers can play and stream older games via Gaikai, according to Gaikai CEO Dave Perry. It's part of their "Everything Everywhere" philosophy.
While I can hear some of the internet groan at the prospect of having to cloud-play their older games, it's a decent solution that's not too pushy on the hardware front (at least in terms of having to include extra hardware just for compatibility's sake) and can theoretically last through multiple generations. I could see this solution being available for gamers to play PS4 games with by the time the PS5 and its successors join the fray.
Check out ALL the PlayStation 4 coverage from today's event here. Console specs revealed, new controller detailed, and tons of games announced!