There isnt a server transfer atm so they can balance the populations between servers, its why some servers get temporerily closed when thier population gets too high (mainly saw it at release), I dont think we will get server transfers till after the ps3 release or you will have some servers with really high populations and some with no one on, Besaid, Selbina and Mysidia would have a huge eruption in population while Gysahl, Karnak and Istory would have no one on.