how long will PSN be down for?

Yes but the latest from Sony is: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.

and

Sony wants you to know that it it will very hard to bring back the Playstation Network just as soon as it figures out what's wrong with it. The entire process, says Sony, could take "a full day or two." I suggest that Sony check if the power is on. That almost always works for me.

The game network went offline Wednesday evening and remains unavailable for gamers attempting to connect from PS3s and PSPs in both the U.S. and Europe. Suuuuuuuucks. Funtastic game experiences have sadly been replaced by a "the server is currently down for maintenance" message, which has far less replay value than you would think.

Sony's message on its official Playstation Blog does not inspire much confidence: "While we are investigating the cause of the Network outage, we wanted to alert you that it may be a full day or two before we’re able to get the service completely back up and running. Thank you very much for your patience while we work to resolve this matter. Please stay tuned to this space for more details, and we’ll update you again as soon as we can."

Nobody actually knows when the PSN will be back up. But the Sony Company is saying that whenever they can fix the problem that happened in the PSN, then the Network will be working again.

It should be back up by april 25 at the latest

500 billion years

How are we suppose to know?