Update: The PSN is now back online.
According to Patrick Seybold, the Director of Corporate Communications & Social Media at PS Blog today:
As some of you may have noticed, we’ve temporarily taken down some functions of PlayStation Network - specifically access to the PlayStation Store, account management and registration.
Online gameplay will remain uninterrupted.
We thank you for your patience and will report back here as soon as the Store and registration functions are back online.
So at least it's confirmed, eh? Still meh though! More PlayStation 3 News...