The Playstation Network is finally starting to come back up. Playstation will be “phasing in” the online gaming and store functionality over the next few days based on geographic region. Right now you can download the new software update regardless of where you live.
Updated as of May 15 3:04am EST: The Playstation network is restored in Ontario and all of Canada! Confirmed in Waterloo, Toronto and Victoria.
The shaded areas have the service restored so far in the US: