Previewed at WWDC, launching in the fall.
AT&T Disables Free iPhone Wi-Fi (For Now)
No official announcement had been made, however, and AT&T representatives reportedly declined to comment. Today, many users are reporting that the free iPhone access has been removed and users are unable to log-in with just their phone number. This appears to be true at locations that were verified to offer the free Wi-Fi access just days before.
Based on the screenshot and wording of the login page ("Free AT&T Wi-Fi for iPhone"), there can be no doubt that the service was intentional, but it appears it may have been launched prematurely. Regardless, we still expect the service to be officially announced in the future.