If you've got some time to kill you might want to head over to the 
Bioshock 2 teaser 
website as 2K has started to populate the site with content.  There's some interesting images on the site include what looks to be a new protector (maybe Big Sister?) as well as a few other clues to the existence of some other kind of underwater facility.  I know the original holds a special place in the heart of a lot of gamers so it will be interesting to see what 2K Games does with the game.