Yes. It is free. The PSN wants a credit card number if you wanna buy stuff. I buy things from time to time. I didnt "have" to enter my credit card. (however on account creation they ask for you to do so, but you can skip it) I dont see why they would "require" a credit card. They are sposed to start selling 'cards' like the Wii does. So I dont see why you would need a credit card to sign up.
PSN ID: Kwaad
I fly this flag in victory!