Well this is flying on there website right now
http://www.playonline.com/ff11us/polnews/news19199.shtml?utm_source=twitterfeed&utm_medium=twitter
Thank you for your continued support of PlayOnline and FINAL FANTASY XI.
As a result of an attack on our computer network, there is a possibility that information pertaining to some users has been compromised including the PlayOnline ID, PlayOnline password and certain other details obtained during registration. We have taken measures as soon as the attack was detected, and have limited the potential breach of information.
If you have linked your PlayOnline ID to a Square Enix Account, your account will be safe due to the nature of the information possibly breached. Please be assured that sensitive information such as your credit card number has not been compromised.
To prevent any misuse from accounts potentially compromised during this incident, we have changed the PlayOnline password for all those affected. We will be sending the new PlayOnline password to you by regular mail to the address registered in our records. We apologize for the inconvenience, but you will be able to login to PlayOnline using this new password. We have also sent out details on how to reset your password through our Information Center to those with a valid e-mail address, during the early hours of June 4th.
Those who can still login to PlayOnline using their current password are unaffected by the contents of this e-mail.
Please note: Square Enix employees will not ask you for your PlayOnline password regarding this incident. Please remain vigilant of any phishing attempts disguised as correspondence from Square Enix.
Thank you for your understanding, and we again apologize for any inconvenience caused.