http://www.sfgate.com/cgi-bin/blogs/techchron/detail?entry_id=65436&tsp=1
Valleywag said a group called Goatse Security, which has exposed other security problems in the past, found the hole. They were able to exploit a function on AT&T's website that allowed them to obtain e-mail address when they entered in the ICC-ID of iPads as part of an HTTP request. The ICC-ID authenticates a user on the AT&T network.