[fnordsensei]

I have one too (which I've since swapped for an email I actually use). I'm not one hundred percent sure, but I think it was the only option for a while (inherited from MobileMe, perhaps), or at least it wasn't clear that you could/should add another email.

Either way, Apple could definitely do something with regards to make it easier/more obvious to replace it with a useful email address, especially now as it becomes a federated identity provider.