Yes, I had a 5G and the plastic mounting of the headphone jack broke
However, Apple nicely replaced it with a brand new one within 10days
I was a little peaved as i asked the Apple support on the phone whether they were going to fix it or just replace it. They said they would fix it. They in fact replaced it. Nice! i here you say, not really as i was hoping too maybe offer up a bit more money to get a 10 or 20G even.
Headphones don't seem to be apple's designing strong-point, as my girlfriend bought me the iPod remote/headphones for xmas and about two weeks later the cable sleeving conecting the remote side to the iPod is now seperating from the moulding of the plug - thus exposing bare, albeit colourful, wires. The sound quality is not impared at all - i just make sure that i don't unplug that end and use the remote part as an extension cable to whatever device i'm sending the source signal.
Edit: Although the remote/headphone was bought from a reseller in london, after taking it back there, reciept in hand; i was informed that i have to go through apple support and send them to belgium 'to be fixed'. So i'm waiting till they properly give up the ghost (still within 6 months of purchase though) and get replacements or new ones.
That measn it's not long before i sell my 5G and new remote headphones for whatever apple decides to bring out as a replacement.
Bring It ON!!!