MrHappy has posted something about the new server system called data centers.
Remember to check the data center that belongs to your server or else you may log into a Data Center that your FC and everyone else in your server are not in.
http://www.youtube.com/watch?v=DuSWyGxoU54
Elemental
Aegis / Atomos / Carbuncle / Garuda / Gungnir / Kujata / Ramuh / Tonberry / Typhon / Unicorn
Gaia
Alexander / Bahamut / Durandal / Fenrir / Ifrit / Ridill / Tiamat / Ultima / Valefor / Yojimbo / Zeromus
Mana
Anima / Asura / Belias / Chocobo / Hades / Ixion / Mandragora / Masamune / Pandaemonium / Titan
Aether
Adamantoise / Balmung / Cactuar / Coeurl / Faerie / Gilgamesh / Goblin / Mateus / Midgardsormr / Sargatanas / Siren / Zalera
Primal
Behemoth / Brynhildr / Diabolos / Excalibur / Exodus / Famfrit / Hyperion / Lamia / Leviathan / Malboro / Ultros
Chaos
Cerberus / Lich / Moogle / Odin / Phoenix / Ragnarok / Shiva
A data center selection menu has been added to the title screen.
If you have characters on multiple Worlds, please select the appropriate data center for the character you wish to play as before logging in.
If a record of your most recent login still remains, the appropriate data center will be selected automatically.