Incidentally I should note that I am in the minority of programmers who are extroverts.
As am I, and of course I assume everyone else is like me, which probably had something to do with my earlier comment ;-)
I personally like working in a semi-open environment, not separated from my co-workers by walls and a door, but by natural spatial separations set up by paths and common areas (something like Christopher's pattern 152, "Half-private office" from "A Pattern Language"). I feel comfortable putting on my headphones and ignoring folks when I need to not be interrupted, but like to be generally available. It also helps me give my hands much needed breaks by having natural, social interruptions.
I would be quite interested to see how "introverts" respond to this type of an environment, and whether it has an impact on their general outlook. I suspect if I spent most of my waking day in a room by myself with a door closed that I would consider myself more introverted than I do now.
Okay, I'm done rambling now ;-) Thanks for the citations.