I believe third party programs are legal as long as they don't give the player an unfair advantage, ie: FRAPS.
Printable View
and also this
http://aikar.co/ff14windower.html
Again, it is just windowed full screen. Not actually full screen.
What they need to do is add in game options to change the type of screening the game does. Full-screen, Windowed, and Windowed(Full-screen)
Fix coming along with 2.0. I'm not going to try trawling for the dev quote.