Play Your Games From Multiple Consoles If You Have PS4

Sony has confirmed that players will be able to access their PlayStation 4 game library by logging into their account from any console.
Speaking at the Develop conference in London, Sony R&D senior team leader Neil Brown explained that the process is possible thanks to “Play As You Download,” which will allow players to begin playing a game even before they’ve downloaded the entire thing.
“You can visit your friend’s house [and] log into your account and play any game from your digital library, which is good,” Brown said. “But how useful is that if it takes half a day to download the game you want to play? With Play As You Download you get much quicker access to at least the first section of the game so you can start playing quicker. So this makes a digital library a practical option in the real world.”

Brown explained that players also won't have to wait to install games to their consoles.
“A similar system also works on Blu-ray. Chunks are automatically copied to the hard drive in the background,” he said. “This means that after the first few minutes your game can rely on having faster read speeds from the hard drive, which provides a better experience for players. And this is a completely background process for the player. They don’t have to wait for anything to install before playing the game. The game will launch as soon as the disc has been put in the drive.”