Just announced. Share Play is going to be a game changer. Basically you can "pass the controller" to a friend anywhere, through the internet even if they don't own the game.

Also includes Youtube upload and new ways to find friends

Since we first unveiled PlayStation 4 and its deep social capabilities, including the SHARE button, we’ve seen an outpouring of excitement from gamers. Players have rallied around a culture focused on sharing epic gaming moments through Live From PlayStation, interactive streaming, SHAREfactory, What’s New and Photo Mode in exclusive PS4 games like Infamous Second Son and The Last of Us Remastered.

Let’s go a step further together. Let’s go from sitting back and watching friends play to actually jumping into games remotely and sharing great experiences together in real time. Today at the PlayStation press conference at Gamescom, we will deliver on yet another promise from the PS4 announcement and introduce Share Play, coming to PlayStation 4 later this autumn.

The best way to think about Share Play is like a “virtual sofa”. PlayStation 4 will create an online local co-op experience by allowing you to invite a friend to join your game—even when they don’t own a copy of it. With this first-of-its-kind feature, you’ll be able to play games with a friend just as if you were together in the same room. Let’s say that with games… you’ll be able to invite your friend online to play as part of your Club in DRIVECLUB.

With Share Play, you can even jump into a game to assist a friend. For example, if there is part of a game that you can’t quite finish, you can invite a friend to take over your controls. Like handing over the controller to a friend on your couch, your screen will be shared as your friend gets through the part of the game that has been giving you trouble—can’t get past that part in The Last of Us: Remastered when you’re hanging upside down? Get a little help.

Share Play will be coming to PS4 as part of the upcoming system software update v2.00, scheduled for release this autumn. The update will also add highly requested broadcast and video share features, including both uploading you game play footage and dedicated app support for YouTube, which we mentioned on stage at E3. Finally, What’s New will get enhanced real-time activity through friend-of-friend suggestions, allowing instant access to friends’ and recently played games’ broadcast More features to come when v2.00 is available, and will let you know.

We always want to hear your feedback and look forward to what you are most excited to experience together first Share Play when the feature comes to PS4 this autumn. What will you co-op first with Share Play?

http://blog.eu.playstation.com/2014/08/12/upcoming-ps4-system-update-v2-00-add-share-play-youtube-come/

I wonder about the details of how this works. Pretty bold idea though.

This could be a game changer. Try any game even if you don't own it!

Both have to be PS+ tho I think.

Do you give your friend the game and he runs in his machine or you stream your game to him to control it?

Me thinks a DRM debacle is about to ensue....

OP updated with details. Coming this autumn/fall

YouTube app. is implied right?

Edit: Some Idiot didn't read the article first. Good a YouTube app..

How will it work for the other player without downloading the game? Like PSNow?

The update will also add highly requested broadcast and video share features, including both uploading you game play footage and dedicated app support for YouTube,