To be honest the credit card details aren't the worst part of it. Sure it sucks but what will happen for most people is that they'll cancel their cards and get new ones so those details won't be useful for very long. Even if they do get used to make some purchases, most banks have fairly strong anti-fraud policies so the impact to you is likely to be quite small - a bit of inconvenience but probably no financial hit.
What is worse is that a lot of your identifying info including your email address, physical address, telephone number and PSN password has been compromised. A lot of people are dumb and use the same passowrd (or simple variants of it) everywhere so I'd expect given a sample the size of the entire PSN customerbase to have a lot of not very security minded people. Why steal your credit card details when they can log into your email, get your bank details and order a new one that you don't even know about? Or apply for a loan? Or go to your Amazon account and buy lots of random stuff using your saved payment details?
If you used your PSN password anywhere else, you should be going around and changing it everywhere you can even if you never bought anything on there before.
To be honest, yes the stuff did get compromised, but it seems to be like its an attempt by Sony to divert the blame, I've seen alot of my CoD playing friends having random facebook spouts of anger at the hackers causing this, when tbh, it's Sony who have fucked up just as bad with their security policy's.
Most (not all) web developers I know seem to think plain text is perfectly fine for storing passwords, mainly I think because it's a hassle to do the encryption and there more worried about the colour of a light box or some shiny thing. Data security is then in there view down to the DBAs or SysAdmins and nothing to do with them.
Web developers in my opinion generally deserve a very special level in hell, three poxy sites I now look after are complete PITA to change, when all they every really needed was wordpress and a good skin (anyone know a good wordpress skinner BTW ? I have three sites that need attention )
Playstation Online still down and I can't get Demon Souls to load (which I guess is related), I'm oddly not concerned about my details being nicked but do begrudge when I do have some time to kill that I can't do it playing a game which should work offline.
I was so miffed I finally got around to plugging the 360 back in, which will be ready for LA Noire, that looks like it's gonna be AMAZING