IGN has a new interview with Ken Levine, as well as BioShock the also cover the wider subject of First Person Shooters.

IGN: Is there anything else you wanted to talk about that's relevant about BioShock right now?

Ken Levine: What was cool is that at E3 people were excited and were exposed to the world of BioShock. And now we're really excited about taking all these theories we had of BioShock and the gameplay, and putting them into practice.
The most exciting thing about working on something new and innovative is that it's a real learning experience. When we made SWAT 4, we kinda knew what we were gong to end up with in a lot of ways. It was really us just trying to make a better version of SWAT 3. That's what the publisher asked for. So for us, it was fun to work on it as craftsmen. But it wasn't really exciting because we really weren't leaning that much.