Valve says that hackers have likely stolen encrypted payment information, including credit card numbers, belonging to users of the Steam online game distribution platform. The data theft occurred during an intrusion last year; the information was taken from a backup database. Valve acknowledged the intrusion in November 2011, and said at the time that there was no evidence of the payment card data having been taken. Valve notified Steam users of the situation by email before sending official breach notification letters. An investigation is ongoing, but UK authorities have a man in custody who claimed he had downloaded Steam usernames, passwords, and credit card information.

http://www.csoonline.com/article/700059 ... valve-says

They've said that its unlikely any sensitive data was obtained (ie credit card numbers) since all this stuff was encrypted. Probably nothing to worry about.