I had .mac a long time ago, and its expired. I never upgraded to mobileMe either and my My AppleId is my .mac email address and always has been. Accessing iCloud via Web Browser has the correct emaill address, a .me address and I can send and receive email to the address. However when setting up iCloud on iOS5 it's trying to use my original @mac.com address and failing and there does not appear to be any way to change it on the iPhone. I checked my AplleDi acct and saw that there were three email addresses, my main email address, the expired .mac address, and the new .me address. I removed the .mac address but still can't get my iPhone to use the proper email address.