Sony confirmed a few months back that the PS4 will be getting its own companion apps for smartphones and tablets. From the small demos they've shown off there is a number of things you can do, such as send messages to friends and download games to your PS4 when you're away from it.
Shuhei Yoshida confirmed some upcoming features to expect from the PlayStation companion app.
It’s an application that anyone can download for free on iOS and Android devices.
There are a variety of things you can do with it. You can connect to your PlayStation profile, and send messages – even voice messages – to friends between your smartphone and PS4.
A friend on PS4 can also send out an invitation for a multiplayer game, which you can then check on the App, and you can also purchase PS4 games from PlayStation Store. Your game will immediately start downloading while you're away.
Sony have also confirmed that they will over 'second-screen' gameplay functionality. For those who don't know what 'second-screen' is - a game may require you to draw something, you can draw it on your tablet and then see it appear on your TV screen. Of course there is much more you can do and Battlefield 4 is taking advantage of it for next gen consoles.