Bioshock publisher Take Two had taken Cayman Islands based Name Administration to court over the Bioshock.com, surprisingly they lost the case as the World Intellectual Property Organisation panel found that Take Two failed to show that "the Bioshock website has been registered and is being used in bad faith". Name Administration registered the website a few months after rumours of the first Bioshock surfaced, and after taking a look at the website it's hard to see any point to it other than leeching off Take Two's intellectual property.
If you want the official Bioshock website, head over to www.bioshockgame.com.