Well, time to change my password. I am never saving my CC info on Steam (or anything else, for that matter) again.
Also: just a short statement (not even an apology) on kotaku/gamespot? Not even an detailed explanation on what happened? Nothing on the homepage of the software, no e-mail advising to change our password or warn us that our data may have been compromised? Nothing?
What are the odds of a class action being taken against Valve? This isn't a jest: such a huge security breach, with a lot of personal infos being leaked out (e-mail adress, phone number, country, account name, 4 last number of CC, even your home adress) is intolerable. This should never have happened. This shouldn't have been even remotely possible to happen.