I know this has been in the news lately but just in case......
Sweetbay and Hannaford Market Data Breach
A breach into the computer system of Maine-based Hannaford Bros. Co. supermarket chain resulted in the theft of up to 4.2 million customer's credit and debit card numbers from more than 200 stores including all 165 Hannaford stores in New England and New York State, and
106 Sweetbay stores in Florida. Also affected were certain independently owned retail locations in the Northeast that carry Hannaford products.
The data appears to have been stolen between December 7, 2007 and March 10, 2008. It has been reported that the theft of the account numbers did not provide enough information for thieves to access cardholders accounts. This means that in cases where fraudulent activity actually has taken place using the stolen card numbers, the thieves were able to match stolen account numbers to names by other means, perhaps through phishing.