North American Community Team Leader Regina Buenaobra announced today that the free World Transfers will be limited to one transfer every 24h.
We want to give you a heads up: Starting with the new WvW rotation tomorrow, we will limit the free World transfer to one transfer every 24h. This should address some of the unwanted WvW exploits we have seen, while still giving people the opportunity to switch a server to play with their friends.
Source: forums.guildwars2.com