While their stance on disc based sharing is pretty basic (if you have the disc you can play it) and made for a good laugh in a commercial during E3, Sony has just explained their digital sharing policies. In an FAQ posted on their official website, the company explains the process.
Every PS4 user will have a registered “primary console.” When they download a game to that console, every user can play the game once its downloaded regardless if they own it or not. Also, if you happen to have a PlayStation Plus subscription on your account anyone, under any username on that console can enjoy “certain benefits” including online multiplayer.
When you are away from your console you can download the game to another PlayStation 4 under your username. The catch is that only that user name will have access to play the game. The same goes for PlayStation Plus benefits. Unless of course other users have their own subscription. The username sharing has its limits as well. You can use up to 2 systems at once. Your “primary” PlayStation 4 and one other system.
The PlayStation 4 will launch in North America on November 15th and in Europe on November 29th.