I, too, think it's unfortunate that people listen to music so much in public. I don't think it's wrong, per se, but it does create barriers. I also think it can ruin the enjoyment of music. I remember when my older siblings used to listen to LPs. Listening to music was more of an event. They would sit down with their friends, turn on a record, and actively listen to the songs. The ubiquity of music can turn it into nothing more than an audio backdrop, rather than something to be appreciated itself.
I admit that I own both an ipod (for running) and a GPS. I never would have owned either in college, but now that I'm actually making real money, they don't seem so excessive.
The ipod is something that I use most often on my morning shakeouts. It makes it a little easier to get out the door when I'm exhausted. I seldom choose to wear it in the afternoon or evening, because then I'm usually engaged enough that running is far more intrinsically enjoyable. Also, the Shuffle is so cheap and small, that it makes running with music much less intrusive than it used to be. I also make a point of pausing the music frequently, for safety purposes (whenever I cross a street, if I get to a crowded area, before turning blind corners, when I'm forced to run on a busy street).
As for the GPS, I use it once or twice per month. It's nice when I'm traveling, because I can head right out the door and run exactly as far as I want. I've also used it occasionally to simulate a track workout on the roads. However, most of the time, I'm running loops that I know by heart, and I'm saving my hard stuff for the track, so the GPS isn't too important.
They're both nice things to have, though I consider them both dispensible. I will admit that I'm not quite secure enough in my image to sport the ipod and GPS at the same time.