MMO Culture says that Sirius Entertainment, the game's original developer, "deemed that various ongoing critical bugs and server instability could not be solved." The site also reports that all players who purchased cash shop items will receive refunds.
[Update: The official word from Aeria Games is this: "Aeria Games confirms that the Korean beta version of Lime Odyssey: The Chronicles of Orta is shutting down. The company also confirms that this will not affect the development or rollout of Aeria's English language version. Lime Odyssey is currently in an expanded Alpha play test and will be published in North America by Aeria Games in 2012. Sirius, the developer behind Lime Odyssey, continues to develop and support the North America version."]