It has been confirmed by several developers according to a forum post on NeoGAF that PSN is back online and select developers have been provided access to test the new services. Access for general public is still a No but hopefully soon.
Okay, so this was mentioned in the old thread by a QA tester and since then I have had other developers confirm to me that this is the case. The internal PSN developer network is online again, at least it seems for some, although things are still a bit shaky at the moment such as lack of new account sign up.
Looks like the full network, at least the online play/account part of it, will be back soon.
Update: QA started earlier this week on online games and has been running smoothly.
If the internal testing of the Playstation Network services has been started, it won’t be long before general public will be given access to the service.