Reader "deadipod" sent in a link to this page detailing the cause of his non-mounting iPod.
...after I decided that I did not want Apple to replace my 'Not mounting anymore' ipod [for] $250. I had some files I worked on last night at home and needed them. I wasn t going to have a replacement. so before deciding on getting a new 10 gig I decided to see if I could remove the HD. (Apple doesn t fix ipods, they replace them)
At this point I knew the HD was fine since I could play mp3s and I could recharge the ipod too, also all harware tests were working. But I noticed that if I moved the firewire cable a bit while it was plugged the ipod would not charge anymore. I knew it was a connectors issue then.