leadership is the ability to a) identify goals important to enrich wikipedia content as an encyclopedia, but also, on a different note, to b) identify different methods to increase engagement by the public with the wikipedia community. these goals can be totally divergent, sometimes, but they both have importance.
in addition leadership is the ability to c) identify areas where wikipedia procedures need to be improved, or made easier to understand; d) places where new resources need to be provided, or existing resources need to be improved, for the benefit of the wikipedia community.
sorry if my answer above diverges from the initial question somewhat. I realize my answers tend more towards the prosaic, and towards items more specific to wikipedia itself. however, that is the essence of how I perceive the concept of “leadership,” in the specific actual ways that would give it some real and meaningful basic relevance to the wiki community. I sincerely hope that’s helpful.