Mostly in offices. I like it ok - ironically, it tends to reduce overhead because I can swivel my chair to ask a question rather than waiting for an email or IM response.

We all have headphones that we wear as a "do not disturb" signal. I feel most productive on days when I can dive in and wear my headphones for most of the day.

I think I'd like working by myself if given the chance, but I've always worked for fairly traditional companies.