If you live in the UK, you are now able to subscribe to the service. The current price in the UK is £12.99. The price for the rest of europe at the moment is uncertain. PS Now announced this on their official blog. The service will offer more than hundred different titles to people who subscribe. Games will be available for the PS3, PS4 and the PS Vita.
The recomended speed for this service is at least 5 mbps from Sony. This service is developed by Gaikai who developed it. They announced the acquisition during the reveal of the PS4. PS Now is getting new games each month to its selection. You will be able to stream games from the PS3 library on your PS4 as long as you have an internet connection as an example.