If you received this e-mail in your inbox, that means you'd better reset all your passwords and check your credit-card for purchases made in Singapore or something.
Here's an article from two months ago, detailing on PSN being hacked: http://arstechnica.com/gaming/news/2011/02/report-psn-hacked-showing-stunning-lack-of-credit-card-security.ars Apparently, there was an ability to view and change strings being sent back and forth, but only for your own personal connection. Now hackers have found a way to do that with other people's strings. http://www.youtube.com/watch?v=oF29asqCv4Y#ws