Kojima Productions have also announced Metal Gear Online will be off in Japan as well. Square aren't charging for subscriptions to FFXI and FFXIV in April.
"Due to the continuous earthquakes occurring in the eastern regions of Japan since March 11 2011, the power companies in Japan have encouraged everyone to cooperate by conserving as much energy as possible as it is feared there will not be enough power supply,” Square Enix's official statement to the server closure.
“To conserve power we are temporarily stopping the MGO servers. Timing for the recommencement is TBD. Sorry for the inconvenience," Kojima.