Can't log-in either. POL has been stuck in the 'can't play during maintenance' screen for nearly 3 hours now.
People over at FFXIAH.com have been talking to some of their friends that CAN play and it seems the issue has to do with what area you logged out at before maintenance.
Some people also say it has to do with SE altering the Behemoth event, but that seems a bit farfetched to me.