It sounds like you're mixing up email with apple ID.
Your iCloud email will always be @me. You can change your apple ID as I changed mine from @hotmail to @live. My apple ID has an iCloud @me.com associated but I use my @live.com for my apple ID.
I'm referring to the Apple ID directly and whether or not it can be changed to and from an iCloud @me address. When an @me address was created from mobileme it created an Apple ID which could not be changed. I'm curious if an @me Apple ID created through iCloud can be changed to @gmail or whatever down the road.