Sony's PlayStation Now game streaming service is pretty similar to the GeForce Now service that Nvidia offers. You pay $20 a month to play PS3 games on the PS4 or PC via OnLive-style streaming. Today, Sony announced that it's adding the ability to play PS4 games on the service, something that could make it pretty interesting for PC gamers that don't want to shell out for console hardware.
This upgrade to PlayStation Now could be a response to Microsoft's Xbox Game Pass announcement. That service is scheduled to debut later this Spring and will allow Xbox gamers to pay $10 a month to download and play Xbox One, Xbox 360, and even original Xbox games. Unlike PS Now, the Xbox Game Pass isn't available for PCs, but it's also not based on streaming, allowing for local game downloads.
You can already play PS3 games on the PS4 and PC using Playstation Now, so if you missed some classics from last generation, that might be a good way to enjoy them. Besides a vague "later this year", Sony didn't say when PS4 games (or which of them) will be hitting the service.