According to this “resume” from Sucker Punch’s rendering programmer, inFamous: Second Son is a PlayStation 4 launch title. The resume indicate that the game is slated for a 2013 release date as a PS4 launch title. The game will ship in Q4 2013.
A second resumé comes from Andy Martin, an employed at Sucker Punch. He notes the game is set for a “2013 announced.”