When you complete the PS3 version of Bioshock you are in for a treat - a short teaser for the sequel named Bioshock 2: Sea of Dreams. Not much to say about the teaser more than that it features a girl in a white dress (little sister all grown up?) with a Big Daddy doll in her hand looking out over the sea (Atlantic coast) with her back to the camera. Behind her the sand is raised to form a city resembling Rapture... Can't wait to hear more about Bioshock 2: Sea of Dreams - the PR guy has been hinting at a reveal event soon. So hopefully it will be shown before the end of the year.
If you can't be bothered with finishing the PS3 version of Bioshock the teaser can be found on Youtube.