The Advanced Media Network has a half hour interview with Ken Levine and Paul Hellquest of Irrational Games.

The video, in WMV format, weighs in at around 95MB, however there is a transcript available.

Ken: And we designed it about, I think January of 05, with the design document which was pretty solid, with the core design, then I think conceiving the AI in the world. The big step up from Shock 2, is your relationship with the AI's and the AI's relationship with each other. We'd just done SWAT 4, we should have done the thing, and Paul's the designer on that of AI's that outflank each other and take cover and, everybody's done that and what's next?

And a big part of BioShock became this "AI ecology" and that was a big step in development for it and that was about a year and a half ago, two years ago, and then, the aesthetic component, was the final big step of getting this whole look, I don’t know if you've seen the screenshots.....it's a really unique look, and once we got that it was just "boom, boom, boom" (pounds table for emphasis, shaking the camera)