The PlayStation App will launch alongside the PS4 later this year as a free download for iOS and Android platforms.
Announced at TGS a few weeks back, PlayStation App promises to enable users to take the PlayStation Experience with them whenever they're away from the console. You'll be able to keep in touch with friends, compare trophies, view friends' activity (which includes watching recorded or live-streamed gameplay), and access the PlayStation Blog.
"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," explained Sony Computer Entertainment Worldwide Studios President Shuhei Yoshida.
"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."
The app will also enable second-screen gameplay experiences on enabled titles.
"There are many big publishers creating their own apps for their games, like Watch_Dogs or Battlefield, and that's great," Yoshida added. "But smaller developers can use PlayStation App to connect to PS4 and load an application, like drawing software for example, so that you don't have to download and install a specific app on your smartphone. It's open to all PS4 developers to use."
Source: PlayStation Blog