"I rode on the bus last year with a bunch of NYU students, and it seemed as if every one of them was plugged into an i-pod or a Dell Jukebox. The same with every young person you pass on the sidewalk."
I have a Treo 650 (phone/pda) w/ 2gb SD card for mobile music duty. I travel a lot, and listen to it in airports, on the plane, while I'm working, etc.
When I'm in public places I prefer to not listen and have situational awareness, instead.
I'm in two minds about it. On the one hand, I can't help remembering that early story by Ray Bradbury about a society where everyone is plugged in and no one is open to the outside world or to other people around them.
On the other hand, when I do repetitive commuting, I have taken to listening to MP3 books on a CD player, and I'm thinking about transferring them to some sort of i-pod player that would be a bit lighter and more convenient.