http://www.gamespot.com/articles/gamescom-2014-ps4-system-update-2-0-introduces-sha/1100-6421674/Details on exactly how Share Play will work weren't shared, but, put simply, it allows you to play local multiplayer games with a friend who is not physically with you. This works in two different ways. In one case, you can (virtually) hand off your controller to a friend as if you were both sitting in the same room, presumably so you could take turns with a single-player game. In the other case, you can invite someone to play a game's local multiplayer with you--again, without actually being in the same physical location. Share Play requires PlayStation Plus.
This seems like something extremely interesting for Playstation that could win a lot of people over. Will you use this feature?