Starting on October 28, you'll be able to share your games with friends -- even if they don't own them. We'd heard about a feature called 'Share Play' before, but now you get a chance to see it in action.
What's so cool about Share Play is that it lets your friends watch you as you play, if not straight up take control of the action on the screen, without actually having to own or download the game you're playing. The only requirement is that your friend is in your party.
To contextualise this feature -- say you get stuck in a game, and your buddy across the country is an ace at that genre. You could get that friend to play that part of the game for you, without even having to be in the same room.
Even better, you can let your friends be "player two" in the game you're playing, even if they don't own the game. Sony does note that both players will need PlayStation Plus, however. Still, it's a neat feature overall, right?