Sony's streaming game service is PlayStation Now
Through this service, PS1, PS2, and PS3 games will be playable over the internet on PS3, PS4, PS Vita, and also on devices like tablets, smartphones, and televisions. Even non-PlayStation devices will eventually support PS Now.
Playstation Now is a subscription service where you pay a monthly/annual fee to have access to an emulated library of Playstation games over the past two decades. Or you can pay a rental fee for each individual title. It's the Netflix of Video games.
This is a very promising idea, but I would like more details regarding pricing and available content before I get too excited. PS Now is launching this summer, so the details should start trickling out soon.