Based on the information Valve has released, users' usernames, email addresses, passwords, billing addresses, and encrypted credit card information was stolen.

Unless you hear more later on, I would keep an eye on your credit card transactions, but not really be more concerned than that. There's nothing yet that says that the encryption on the card info has been broken. However, definitely do change your Steam account password, and if you have any other online accounts that use the same password, change the password on them too.

Just my $.02...

thanks for the heads up