One of the new features in the just released iOS 6 beta 3 is the new arrival of @iCloud.com email addresses. A replacement for the now defunct @me.com addresses that MobileMe users used to have, the new system was spotted by MacRumors, and the addresses will be handed out to users signing up for new Apple IDs or enabling mail on their iCloud account:
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.