Apple announced today through the documentation on iOS 6 beta 3 that they are starting to sign up new Apple IDs with @icloud.com instead of @me.com in yet another of move to get rid of everything related to MobileMe.
According to the change-log included with today's iOS 6 beta:
iCloud.com email addresses are now available for iCloud mail users. Users signing up for new Apple IDs, or enabling Mail on their iCloud account for the first time, will automatically receive an @icloud.com email address instead of a me.com email address. iCloud users with @me.com addresses that have been used with iOS 6 beta 3 will receive an @icloud.com email address that matches their @me.com address.
iCloud replaced MobileMe last year and that service has ceased to exist as of June 30.