"Leadership" is as elusive a concept as there is in business—not that that has prevented scores of writers spilling torrents of ink on it.  (The general form of the tautology in this management literature is:  It requires a great leader to build a great organization, but/and the most important characteristic of a great organization is developing great leaders.  Res ipsa.)

CIO Magazine has a perceptive column that actually has something to say about what it takes to lead:  Start with character, teamwork, passion, and persuasiveness.