"Maintenance" is just the default error message when trying to connect to PSN.

If you check the PlayStation.com web page, you'll see that for a number of services (account management, gaming and social, PlayStation now, PlayStation video, PlayStation cue, PlayStation store, PlayStation music) are "experiencing issues" mostly pertaining to accessing content, or online features.

That's not "maintenance" ... It may not be a hack attack, but it's not maintenance either.