Final Fantasy XIV (FFXIV)
will begin merging server worlds in March to help improve the player experience. Players will need to select a new world for their characters to be transferred to before the established deadline, which will take place over two periods between March 1st and March 19th, 2012. Players that fail to select a destination world will be reassigned automatically. The server transfers and mergers will be carried out on March 27th.
For more details, be sure to check out the FFXIV World Merger Details page to find out what’s available and how to select your new world.
Source: FFXIV World Merger Announcement
Update: Square Enix Reassessing Final Fantasy XIV World Merger Process