According to the Official PlayStation Magazine UK, Bioshock is in development for the Sony PlayStation 3 console.
The magazine states many times that the game is in development even though the thought up until now was that the game is going to be an exclusive for the Xbox 360 console.
The magazine mentions that the exclusivity of Bioshock is only a timed-exclusive for Microsoft. This means that the game will be an exclusive on the Xbox 360 but for just a short period of time. It will then be released by 2K Games on all next-generation consoles, meaning the PS3.