We were all really impressed when we saw the BioShock: Infinite trailer last summer, but we haven't had an update on it since. Today at PAX East, Ken Levine and other developers from Irrational Games gave a talk about creating the world of Columbia, the floating city in which BioShock: Infinite takes place. I was able to glean a few new details on what is sure to be one of the biggest games of 2012...