Nelson Mandela talks about this interesting concept of "leading from behind" in his autobiography, "Long Walk to Freedom". In the book, Mandela likened a leader guiding his people to a shepherd leading his flock. According to Mandela, the shepherd "...stays behind the flock, letting the most nimble go ahead, whereupon the others follow, not realizing that all along they are being directed from behind".
"Leading from behind" is a perfect model to adopt when a situation demands "collective leadership". Here the leader empowers different team members to take charge of the team (flock) at different stages, based on their individual strengths (nimbleness). In this style of leadership, the leader sets the vision and then finds appropriate people to lead the team towards that vision.
On the other hand, the traditional style of "leading from front" leadership works perfectly in cases where there is no need for collaborative decision making. Here the leader sets directions, delegates work and gives orders.
A good leader is one who can shift between leading from front and behind as the situation may warrant.