We reported last week that the AT&T Galaxy S III will ship on June 18. Ma Bell is still the only U.S. carrier that hasn’t revealed an actual release date for the phone. Thanks to one of our readers who is an AT&T Premier customer, we can now confirm that June 21 will be the date the handset will be shipped on. AT&T then joins, as expected, T-Mobile and Sprint to the 06/21 launch party; and if you’re a Verizon customer, July 9 will be the date for you unless the nation’s number one carrier decides otherwise. AT&T will also ship the phone “on or around” June 21 to non-Premier customers. Are you getting one?