The news yesterday that Twitter CEO Dick Costolo is stepping down from that leadership role next month has attracted widespread commentary and opinion, not least on Twitter itself. There's credible opinions that Costolo is going because he hasn't evolved Twitter as many observers and critics expected or believe he should have. Indeed, the stock market greeted yesterday's announcement with a 10 percent rise in Twitter's share price at one point. An analysis in the Guardian today - you can … [Read more...] about Dick Costolo: Twitter unfollows the leader as social milestones are missed