Via
IGN:
Gabe Newell announced today that Steam's database and forums have been hacked. According to Newell, Steam's forums were defaced earlier this week, and further investigation led to evidence that the hackers had obtained access to the Steam database.
"This database contained information including user names, hashed and salted passwords, game purchases, email addresses, billing addresses and encrypted credit card information," Newell wrote. "We do not have evidence that encrypted credit card numbers or personally identifying information were taken by the intruders, or that the protection on credit card numbers or passwords was cracked. We are still investigating."
While the hackers may have had access to the data, it isn't immediately clear how much information they actually took, or if any of it has been used.
"We don't have evidence of credit card misuse at this time," Newell added. "Nonetheless you should watch your credit card activity and statements closely."