Apple released a new version of iOS 6 beta 3 today, and in the changelog for that release, MacRumors points out a note that the transition from me.com email addresses to icloud.com email addresses for iCloud users has begun. Users that are signing up for the first time will get icloud.com addresses, and anyone using iOS 6 beta 3 will have the option to get a new icloud.com address using the same email name (in addition to their mac.com/me.com address).
Already, a few users are calling foul, since me.com is obviously a shorter name to type out than icloud.com. But this is the transition Apple has been planning for a while, and so what's done is done. Perhaps Apple will finally brand the Mobile Me-turned-iCloud service the correct way across the board, and everyone who uses it will benefit.
Update: Note that the changeover to icloud.com is not required for current users of the service: Only those who sign up for new accounts (or iCloud accounts that have never had email enabled) will get the icloud.com domain, while those still using me.com can keep their names if they would like. So good news for those who prefer shorter email addresses!