Wraith: I was under the impression that Irrational Games under the direction of Ken Levine were who were primarily the ones who wrote and made Bioshock.
Ken Levine was the lead designer. On BioShock 2 he served a creative consultant (I read this somewhere, though I've just now read conflicting information). But (my mistake here), five of the team members (presumably core) moved over from Irrational (later renamed 2K Boston).
KL: BioShock 2 wasn't the right thing for 2K Boston; it was the right thing for 2K Marin. After BioShock, 2K wanted to grow the company by starting a new studio in Marin, and they asked if it could be seeded with some 2K Boston and 2K Australia developers. They said, "Dude, are you cool with that?" I understood what they were trying to do, so I said, "Sure." All in all, five smart folks from 2K Boston are now at 2K Marin. (
via)
I guess in a sense that makes him creative consultant though haha.
Just noticed in that interview he mentions GOG! And GOG mentioned previously they were talking to him about a deal. Only a matter of time before we see System Shock. :)