With exact dates and info
As we already know, the PS4 version of Final Fantasy XIV: A Realm Reborn will launch on April 14, 2014. Phase 1 of the beta will start on February 22nd, and will run until March 3rd (characters will be wiped in this phase). After that, Phase 2 will start on April 4th and run until April 7th (characters from Phase 2 can be transferred over to the main game).
Square Enix says that everyone with a PS4 will be able to access the beta, and you'll download it from the store. PS3 and PC players will also be able to transfer your data over to the PS4 for the beta, but Square Enix notes that in the retail version everyone plays on the same servers.
However, once you transfer your copy over from the PS3 to the PS4, you'll be unable to play the game on your PS3 -- unless you buy the PS4 version separately. The PS4 version will support updated visuals, PS Vita Remote Play, mouse and keyboard support, and Dualshock 4 touchpad support.
That's a lot of information to take in (both new and old), but at least you know what to expect in the coming months.