Games gonna be awesome!!
On the Official Bioshock Homepage (http://www.2kgames.com/bioshock/), you can download the Main Theme. (don’t search for a download link, the MP3 will be downloaded into your Temporary Internet Files folder) The music reminds me a bit of the score from F.E.A.R. by Nathan Grigg – the main theme is definitely a screepy bit of music, but not very special.
You can hear other pieces of music in the background of the trailers and previews.
Regards, Timo