Cyworld, the South Korean social network that launched in the U.S. with a splashy party in 2006 has packed up its bags and left the U.S. market. The social network, backed by SK Telecom, will layoff its entire U.S. staff and will continue to operate the English-language site from South Korea. The service really didn’t get any traction. Its localization efforts were mediocre at best. I bet other smaller marginal social networks meet the same fate.