First time I’ve seen this, but search for ‘Trafigura‘ on Google right now brings up the Twitter search result for the #trafigura tag.
The reason isn’t that hard to divine – internal links on Twitter for the #keyword things are dofollowed, so the domain power of Twitter, allied to the prominence of this story and the whole QDF thing that seemingly obsesses Google at the moment means that Twitter is going to rank.
Does that make it a good result? No. Twitter’s stream of ‘content’ consists largely of retweeted references to external sites that are hidden by URL shorteners and stripped of any context. In a way it’s kind of like seeing a directory result up there. Does Twitter really tell you more than some of the sites below it in the rankings like The Times? I’d argue not.