First revealed back in August, Share Play is what Sony refers to as a “virtual couch,” insofar as it lets you invite friends to play games with you through the internet, even if they don’t own a copy of the game. You can share your screen so they can watch, hand over your controller so they can help, or give them access to a secondary controller to join in a multiplayer.
But it’s not exactly like playing in your lounge – you can only invite them to play for up to an hour at a time. That said, if you normally kick your buddies out your house after 60 minutes, then this may be a near-identical experience.
At any rate, you can read more about the upcoming feature here, and view a video walk-through here.