Look, in the short term this actually affects me LESS than the bros who hacked MW2 and fucked with all my stats and earned guns and attachments etc, and generally broke the game for me. I haven't played the game for 2 months because of the hack (not a big loss really).
I urge everyone to just go to their local banks and order a new credit card. 7 million people's data has been compromised. The chance of you being defrauded is likely going to be less in the next few days as the hackers (most likely) start selling the data off to the highest bidders or the clients who ordered it to be data-mined in the first place.
If you can, transfer any cash into a 2nd account and leave a small amount in the original one if need be for pocket money (at least until you get a new card).
The new PSN update will prompt us to change our PSN passwords anyway. And then it is up to us, the consumer to update our accounts with our new credit card details (which I won't be doing, the only PSN purchase I've made is Angry Birds).
At worst people who follow the above steps may get junk email. If anyone gets a full on case of identity theft, and can prove its linked to the PSN hack (which may be hard), raise some cash and sue Sony.
It sucks, but it ain't that bad. Just get a new credit/debit card ASAP.