It wasn't public but it was kinda known. Some forums were already talking about it too.
There was a discussion on the beta forum about legacy transfers and a mod closed the thread replying:

"Although the World Transfer Service will begin shortly after release. Details regarding this service, including when Version 1.0 characters will be allowed to transfer from Legacy Worlds have yet to be finalized.

Therefore, I'm going to close this thread before assumptions, theory crafting, and unnecessary arguments run rampant.

We ask that you please be patient and wait for further details on how this service will work."

the link was http://forum.square-enix.com/ARR-Tes...42#post1170542 but is not available anymore.