Apple marks the updated webmail application with a beta banner. Also, you have new alias options, below.
It appears that users with access to the beta iCloud website can send email from the new @icloud.com email domain, but recipients are yet to be able to reply to these @icloud.com emails.
Earlier this month, Apple rolled out the iCloud.com beta website with improved Find my iPhone features, a Notes app, a Reminders app, and a tweaked Calendar web app.
- Apple seeds iOS 6 beta 3 to developers (9to5mac.com)
- Apple launches updated iCloud website for developers with Notes, Reminders, improved Calendar and Find my iPhone (9to5mac.com)