Though the VOA report claims it was Mar 21 ("美国《华尔街日报》星期三发表一篇没有署名的评论，题目是'中国的政变惊慌：中国人明白他们的政府不像其声称的那么稳定'"--with a link which requires subscription or payment), the bottom of this wsj.com page indicates it appears in print Mar 22 (probably online Mar 21).
(ii) Mark Mackinnon, Why the Coup Rumours in China Aren’t Going Away. Globe and mail, Mar 21, 2012 http://www.theglobeandmail.com/n ... way/article2376711/
("the wall of secrecy that Communist Party leadership has built around itself also prevents the development of trust between the government, media and public. It leaves the media with no one to talk to and get real information from when there’s a wild rumour floating about")
(b) The VOA report traces the source of coup rumors to Prof Kong (photo caption: 北京大学教授孔庆东上星期五表示，罢免薄熙来这样的一个好共产党高级领导人相当于“反革命政变”). VOA insults our intellect, as if the whole China, even the entire world, are in dilirium as if we were back in the Salem, Massachusetts, witch hunt. The rumor pointed to Monday night (Mar 19); some Beijingers asserted observing a more-than-usual police presence in a certain part of Beijing, according to various wire (foreign) reports.