http://www.joystiq.com/2013/02/25/diablo-3-on-ps3-and-ps4-will-allow-offline-play/Diablo 3 on PS3 and PS4 will allow offline play
Diablo 3 will not require a constant internet connection for local multiplayer on the PS3 or PS4, Blizzard production director John Hight has confirmed. "You can have four people on the same screen - no split-screen, we just zoom the camera out. Or if you're offline," he tells Geoff Keighley on GameTrailers.
http://us.battle.net/d3/en/forum/topic/7979508440?page=3#49While we think cross-platform play would be awesome, there are currently no plans to allow connectivity between PlayStation Network and Battle.net (this is pretty standard for most games that have PC and console support). As a result, the characters on your Battle.net account and PlayStation account will also remain separate.
In terms of allowing an analog controller hookup for the PC, we don’t have any plans for that kind of support right now. Similarly, since Diablo III for console was designed with a controller in mind, the PlayStation version of Diablo III will not support USB mice or keyboards.
Da gibts echt nix mehr dazu zu sagen...