Credit card providers have been using purchase pattern information to fight fraud for some time. Visa is throwing neural network technology and other analytical techniques to deduce whether a transaction is likely to be fraudulent.
Visa's newest attempt to thwart fraud - Online Banking - MSNBC.com:
"... Visa said that when a card is swiped, its new Advanced Authorization technology provides an instant rating of the transaction's potential for fraud to the card issuer, including whether the card was part of a reported security breach. The issuer can then tell the merchant whether to accept or decline the transaction...."