Heh, I remember these concerns being raised for the first time in my lifetime when the Walkman
came around...so I guess you stayed away from the Walkman and portable cd players as well.
Tinnitus and hearing loss are also fairly common among veteran musicians and DJs, thanks to loud volume, with DJs especially due to having high volume in their headphones while mixing. The iPod itself shouldn't be anymore dangerous than any other device with headphones before or after it.
Yep, I do get the occasional tinnitus squeal, but I'm glad it's nothing permanent. Also, I can still pick most of the high-pitched frequencies that most of my peers can't, and they hurt my ears, especially the vacuum cleaner sound makes me physically nauseous at times unless I wear ear plugs.
I do have a slight hearing loss in my other ear thanks to military service, which the military doctors obviously denied and tested and proved to be non-existent, though, and it seems affect mostly a certain frequency region anyhow and I've learned to cope with it. Still, I sometimes miss by a mile when locating a sound source.