There's a lot of good information floating around in the other thread, so I thought I'd whip up an FAQ for PSN users.
What Do I Do Now?
In case you haven't heard, PSN was hacked and all PS Accounts have been exposed for an indeterminable amount of time. You can check this thread for the details on what was hacked, etc.:
http://www.neogaf.com/forum/showthread.php?t=428561
Because PSN is down, no one can access their accounts to check what information they might have had open to hackers. But, there's still a lot you can do to protect yourself and make sure everything will be alright.
The Odds of Misuse
The good news is that there's, like seventy million accounts out there that have been exposed to hackers, so the chances of your personal information being fraudulently used is, quite literally, one in several million. So, don't panic. However, DO take these following precautions because it always pays to be 100% safe, especially if you have certain info linked to your PSN account:
For all PSN Users
-Change your passwords for all sensitive sites (email) and sites you frequent. Sony has confirmed that there is no way of viewing what your password originally was on your PSN account, so be safe and get those passwords changed.
-It's also important to note that security questions were also exposed to hackers during this incident. So be sure to change your security question and answers with your email provider.
For PSN Users with credit cards linked to accounts
-Chances are if hackers have your credit card info, they would have already used it by now. Still, be vigilant and thoroughly check your statement every week to make sure there aren't any fraudulent charges.
-Credit Card companies are generally great at informing you of misuse, even if you don't have any kind of extra security protection you might subscribe for your card.
-If you want to be extra safe, you can get the CC company to issue you a new card, giving you a new CC number and foiling any would be hackers using your card.
For PSN Users with debit cards linked to accounts
-Debit cards are much harder to fight for fraud activity.
-Because of this, it would be a good idea to go ahead and get your bank to issue you a new card right away. It is infinitely easier to do this than to fight any fraud activity that might arise later, due to the nature of debit cards.
Things you probably shouldn't do
-Close a credit card/debit card account. Doing so hurts your credit rating and is completely unnecessary if you've already got your bank/card company to issue you a new card.
More FAQs:
How do I know what card was linked to my PSN account?
Search your email inbox for DoNotReply@ac.playstation.net. One email should let you know what CC you have on file.
I had a PSN account years ago that I don't use anymore. Am I safe?
You're open to the same amount of problems current PSN users have.
I always delete my CC info after every purchase from PSN.
There might be a chance that that information was exposed to hackers. It's unknown where that CC data is when you delete it- there might be a chance it's still invisibly hidden in your PSN account. No one really knows.
Has anyone had their CC data hacked/used?
Officially, no. There are some anecdotal stories in the main PSN hack thread, but so far nothing "official." Still, be safe!
Is Sony going to compensate subscribers to PS Plus/Qrirocity/DC Universe/etc?
Nothing official yet.
Should I delete all of my sensitive info once PSN is back up?
What was already on your PSN account prior to April 20th is already "hacked," so deleting your CC or sensitive data once PSN is back up isn't going to do anything but help prevent any future hackers from getting your info. Given that Sony is completely rewriting PSN, one would hope that would never happen again.
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I think that's everything, but let me know if I should add any more to the OP!