Strange – AP fact checked this with Hexagon Security Group, Veracode’s Chris Wysopal, and even an AT&T spokesman who didn’t say much but did confirm that this happens.  Sounds like a load of crap to me.  This sort of “glitch” doesn’t just SEEM impossible – has anyone ever heard of a TCP sequence?

…  Several security experts said they had not heard of a case like this, in which the wrong person was shown a Web page whose user name and password had been entered by someone else. It’s not clear whether such episodes are rare or simply not reported. But experts said such flaws could occur on e-mail services, for instance, and that something similar could happen on a PC, not just a phone.

“The fact that it did happen is proof that it could potentially happen again and with something a lot more important than Facebook,” said Nathan Hamiel, founder of the Hexagon Security Group, a research organization…

AT&T spokesman Michael Coe said its wireless customers have landed in the wrong Facebook pages in “a limited number of instances” and that a network problem behind those episodes is being fixed…

via AP Exclusive: Network flaw causes scary Web error.