change your pass NOW http://forums.steampowered.com/forums/ is the proof!  

yes I think but idk how to change one please tell me how!

Parser, I have a Steam account, I've just never used the forums.

Calc, in the client window, go to Steam > Settings > Account > Change Password or Secret Question.

I only have free things on my steam acc. Lol. So I guess I do not have to change my pass.
also:

We do not know of any compromised Steam accounts, so we are not planning to force a change of Steam account passwords (which are separate from forum passwords). However, it wouldn’t be a bad idea to change that as well, especially if it is the same as your Steam forum account password.

GabeN sent out a letter yesterday, accounts are all safe and  on a completely seperate database. The forum one is being re-secured and was not the same place account names/passes are stored. Your games are safe, especially with SteamGuard, although it's annoying if you're the one getting a new computer.

I'm not too surprised they have verified that only the forums were affected, since that was the only place where there had been any noticeable hacking. If people had gotten access to people's actual account details, I don't think they would have bothered defacing it (especially to avoid giving away that they had compromised their DB).

But it's good to know my Steam account is still safe.