"The only truly self-organizing team I know of was Apollo 13 after the pop."
(Thanks for that one, Mom!)
Teams do not spontaneously materialize out of thin air, and just by accident happen to pick a goal that by coincidence is in line with the surrounding organization's objectives. Teams need to be formed, and they need to be given a purpose. Sometimes that is done by a memeber of the team and sometimes by an external party.
I call the process of forming a team and giving it purpose leadership.
Leadership is not only vital to self-organization it is usually a pre-requisite for it. Without leadership there is no team, and without a team there is no self-organization. Apollo 13 teams who are driven by a single, overwhelming imperative pushing them to self-organize are rare in the modern corporate world.
Besides team-forming and goal-setting leadership can serve other purposes in teamwork. These can be guiding the team's daily work, keeping the team on the right course, removing team dysfunctions and in general all activities that help the team. Whether this kind of leadership is needed or not, and wheter it should be internal or external to theam depends entirely on circumstance. What is important that leadership can serve a purpose and is probably needed in one form or another during the life-span of a team.
The idea that leadership is not necessary because teams self-organize is wishful thinking at best.
It will be interesting to hear what Mary Poppendieck has to say about this subject in her keynote tomorrow at Scandinavian Agile Conference 2009.