Statement received from AT&T by email:

In a limited number of instances, a server software connectivity error
resulted in some AT&T wireless customers being logged in to the wrong
Facebook account when they accessed Facebook through their mobile
phones. This error impacted the subscriber identification information
used to automatically log-on the Facebook user if a current cookie was
not available.

The AT&T and Facebook technical teams have been working together on the
issue. The AT&T technical team added new security measures to prevent a
reoccurrence of this issue. As an added measure, AT&T worked with
Facebook to make a change to disable subscriber identification
information as an option for automatic log-on. For customers to access
their Facebook account from AT&T wireless devices, Facebook now only
will accept cookies placed by Facebook or full customer log-on
information. If the cookie isn't current, customers will be prompted to
log in to their account.  With these steps, we've addressed all known
server issues and we continue to work with Facebook to monitor the
situation.

We've also learned of an isolated incident of a customer in Atlanta. Our
investigation shows the issue experienced by the Atlanta customer was
caused by a misdirected cookie on the customer's phone.  We worked with
the customer to resolve the issue. It is unclear how this cookie was set
on the phone.