PS3 owners are reportedly stilll unable to log in to PSN over the bank holiday due to the mysterious server shutdown, and contrary to earlier reports, Sony has admitted that an "external intrusion" was responsible for the outages on the Playstation Blog.
An external intrusion on our system has affected our PlayStation Network and Qriocity services.
In order to conduct a thorough investigation and to verify the smooth and secure operation of our network services going forward, we turned off PlayStation Network & Qriocity services on the evening of Wednesday, April 20th.
Providing quality entertainment services to our customers and partners is our utmost priority. We are doing all we can to resolve this situation quickly, and we once again thank you for your patience.
We will continue to update you promptly as we have additional information to share.
The primary suspect, amorphous hacker collective Anonymous, has denied responsibility (claiming that "for once, it's not us"), but as a leaderless organisation by definition, we'll have to take this with a pinch of salt.
At the moment, naturally, Sony (and its customers) are worried about the security surrounding the credit card details stored on the service. We'll bring you more as it happens.