"Sony's game streaming service, PlayStation Now, is live on PlayStation 4. Using technology acquired from its purchase of Gaikai in 2012, Sony's made it possible to play retail and digital PlayStation 3 games on your PlayStation 4, something the system couldn't do before. Though PlayStation Now will work on a slew of devices, including the PS Vita, Sony Bravia TVs and Blu-ray players, PlayStation 4 is the first device to graduate out of beta status, and our early tests indicate that Sony's off to a great start.
PlayStation Now can be used in two ways: monthly subscriptions and individual game rentals. There are currently two subscription tiers that offer unlimited access to over 100 PlayStation 3 games; you can spend $20 for a single month subscription, or save $15 with a three month commitment for $45. If you want a taste of PlayStation Now before committing to a subscription, Sony also offers a free weeklong trial."