When I worked in a cubicle environment, I used to wear headphones, but wasn't listening to anything. Just to block out any stimulation (plus people hesitate before interrupting you.) I also used to start at 6:30 just to get that magical 90 minutes in before everyone else showed up at 8:00.
An interesting article referencing concentration and attention issues and the folly of multi-tasking. Seems AF would help some of these people.