Scott Dunlap's blog has an interesting entry. He talks about iPods and trail running, and whether these should be banned from trail races.
I'm a newby when it comes to trail running, I've been doing it less than 2 years, and I haven't taken my iPod along for a trip...yet. I am usually by myself, and I want to make sure I hear animals, or horses when I am on a bridle path, or other people around me.
I can see how it could be helpful in a 100 mile race though, to get you through some rough patches.
I do wear my iPod pretty much for every road run I do. I try to keep the volume down, and I am pretty vigilant. But my roads are pretty deserted out here in the country. I may slip off the earphones whens I approach a house (also sparse here) so I can hear/see a dog that might come at me.
How do you manage your iPod use?