I'm surprised there's not an article on this! Yesterday word and video broke on the third Bioshock game!
Bioshock Infinite is actually a prequel with a different setting and story but with similar themes and game play.
This game takes place in 1912 on the flying air city of Columbia, built to show off the prowess of circa 1900 America, but it quickly fell into insanity like Rapture. Where Bioshock used water and darkness, this setting will use air (as in a mile up in the sky!) and brightness.
I think it looks pretty cool. While I loved the Rapture setting a lot, the second game was pretty much more of the same and I'm looking forward to this new setting and story.