http://www.rockpapershotgun.com/2011/11/10/steam-hacked/ Just take care out there folks. I don't want anyone getting their Steam hijacked, even though none have been reported, be careful. One of the best thing you can possibly do is turn on the "Steamguard" feature under Steam>Settings, which requires you to enter in a password emailed to you. And you may want to clear out any credit card info you have saved on your account.
Don't take any chances delete your credit card info under your account settings. As an extra precaution change your password.