OGPlanet offered up a somber press release on the game's web site. "We truly felt that a game like Cabal Online would offer something different and unique for our loyal OGPlanet members, and in many ways, we believe it has. While we had hoped to continue operating the game as part of our services, the game's developers, EST Soft, has unfortunately decided not to extend our contract for Cabal Online," the release states.
OGPlanet goes on to say that item shop transactions were suspended on March 19, and that they "are doing everything we can to compensate our loyal customers."
[Edit: There is an update to this story here.]