Posted on the official BioShock forums by administrator 2K Elizabeth, the specifications are as follows:
Minimum System Requirements:
CPU: Pentium 4 2.4GHz Single Core processor
System RAM: 1GB
Video Card: Direct X 9.0c compliant video card with 128MB RAM (NVIDIA 6600 or better/ATI X1300 or better, excluding ATI X1550).
Sound Card: 100% direct X 9.0c compatible sound card
Hard disc space: 8GB free space
Recommended System Requirements:
CPU: Intel Core 2 Duo processor
System RAM: 2GB
DX9: Direct X 9.0c compliant video card with 512MB RAM (NVIDIA GeForce 7900 GT or better)
DX10: NVIDIA GeForce 8600 or better
Sound Card: Sound Blaster® X-Fi™ series (Optimized for use with Creative Labs EAX ADVANCED HD 4.0 or EAX ADVANCED HD 5.0 compatible sound cards)
The game will require either Windows Vista, or Windows XP with Service Pack 2. An internet connection will also be required "for activation."
Developed by Irrational Games, BioShock has been described as a "spiritual successor" to their previous release, System Shock 2. While project director Ken Levine has attempted to distance BioShock from the roleplaying aspects of that game, referring to it as a straight-up shooter, its unique setting and story have attracted significant levels of attention. The game is scheduled for release August 21 in North America, and August 24 in Europe.