In the open-plan hellhole where I work you'd be hard put to see anyone *not* wearing headphones - damagement are the obvious exception, what with them being in their
ivory towers offices.
What I listen to will depend on what I'm working on and how I'm feeling - there's been a lot of shrieky, guitary stuff of late (eg. Ministry, Napalm Death, Slayer, early Metallica) plus the usual 'classic' rock/metal fayre (eg. Iron Maiden, AC/DC, Motorhead). Quite a bit of electronica, too - ranging from bangin' techno all the way down to full-on beatless ambient. Variety, and all that.
Conversely, when I'm working at home I'm quite content to open the office window and listen to the sounds of birdsong and passing trains.
U2? Taylor Swift? Bollocks to all that ...