Over the weekend the Valve Steam forum was defaced by hackers redirecting requests for the forum to the hackers website.
Now after further investigation by Valve it looks like the hack went
deeper than originally thought and has compromised the main Steam
database.
The main Steam database contained information including user names,
hashed and salted passwords, game purchases, email addresses, billing
addresses and encrypted
credit card information. Although Valve are still unsure
whether encrypted credit card numbers or personally identifying
information was taken.

Valves announcement:
We learned that intruders obtained access to a Steam database in
addition to the forums. This database contained information including
user names, hashed and salted passwords, game purchases, email
addresses, billing addresses and encrypted credit card in
...
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