Bob Sutton mentions an interesting interview with Mark Templeton (photo) which contains some wise quotes (see for instance this one and this one). He also mentions a study on leadership which shows, as Sutton summarizes that "groups tend to pick people with big mouths to lead but that less pushy and extroverted leaders tend to lead more effective teams -- at least when the teams were composed of proactive members)." Here is more information on that study.
Reversing the extraverted leadership advantage: The role of employee proactivity
By Adam Grant, Francesca Gino, and David Hofmann (2011)
Abstract: Extraversion predicts leadership emergence and effectiveness, but do groups perform more effectively under extraverted leadership? Drawing on dominance complementarity theory, we propose that although extraverted leadership enhances group performance when employees are passive, this effect reverses when employees are proactive, because extraverted leaders are less receptive to proactivity. In Study 1, pizza stores with leaders rated high (low) in extraversion achieved higher profits when employees were passive (proactive). Study 2 constructively replicates these findings in the laboratory: passive (proactive) groups achieved higher performance when leaders acted high (low) in extraversion. We discuss theoretical and practical implications for
leadership and proactivity. Read full article.