The Square Enix Facebook page has word that they have temporarily suspended online sales of FINAL FANTASY XIV: A Realm Reborn due to "the overwhelmingly positive response" the just re-launched MMORPG (thanks Eurogamer). Here's word:

Important Notice About FINAL FANTASY XIV: A Realm Reborn - Due to the overwhelmingly positive response to FINAL FANTASY XIV: A Realm Reborn, we are currently experiencing extremely long wait times for users to be able to log in and play. As a temporary measure, we will halt sales of FINAL FANTASY XIV: A REALM REBORN’s digital download products so we can accommodate all of those wishing to play. We are working to expand our server capacity in the coming days.

We sincerely apologize for the inconvenience this causes.