The Cult of Rapture has the details on a new difficulty setting that is being included exclusively with the PlayStation 3 release of BioShock this October, entitled Survivor Mode.
This difficulty will be much more challenging than Hard Difficulty, and will force the players to really conserve their resources and plan their battles. In truth, it sounds a lot more like the Insane Difficulty from System Shock 2, which is a great thing, and I hope this gets added to the Xbox 360 and PC releases of the game at some point in the future.
2K Games has also released an official trailer for the PlayStation 3 version of BioShock, which can be viewed below or on this page here. Love the trailer's music.