My university set me up with a trial Mobile Me account, and on the set-up day when I created my iTunes account, I was told to type in the Mobile Me address, so I did.  I never used the service, though my receipts for iTunes purchases showed up there.  A year later when the service expired, I changed my Apple ID so that my default e-mail is now my university address, but the iTunes purchases are still going to the now-expired account.
I was told that I could create a brand new iTunes account, but if I did I would have to re-purchase all my iTunes content. Of course, I could suck it up and pay for Mobile Me for another year, but I don’t need the service and don’t want to spend the money.
A chat with a Mobile Me tech support pointed the finger to iTunes, but iTunes has no chat tech support.  So I’ve sent an email.
While checking the iTunes tech support forum, I came across a link to a page that said there is another way to check your iTunes purchases.  While following that process, I saw a box pop up that asked me to confirm an e-mail change… I hadn’t seen that box before.
Okay, now that I know I can access my purchase records that way, I can put this annoyance aside and move on to my next task.