Coincidentally, I remembered just recently that this particular special edition iPod existed. It carries model number MA215LL/A and only occasionally seems to crop up on eBay. I could find very few photos of it, one of which is on a fantastic Polish “iPod museum” site, and another in a MacRumors thread.
In trying to find photos of that, I came across some more collector edition iPods which are arguably even harder to find, each engraved with the signatures of Beck, Madonna, or Tony Hawk. There was even one more engraved with the No Doubt logo.
Ugh, my shopping list keeps getting longer.