In a post on Gravity's English website, the company mentions that the English server for Ragnarok Online will be down for about ten days (April 1st through the 9th) while the server actually moves to the United States. After that, instead of just one server for US players, there will be two to handle the massive load Ragnarok has experienced due to its popularity.
There's no word on where the English server will be located in the US or if it's being sponsored by any American company. Ragnarok Online entered into its first beta phase back in September. The client is free and available from Gravity's Ragnarok site, or from a number of other game download pages. No commercial release has been announced yet for the US.