I agree about needing a single leader. Committees are fine but in the end you need one person who makes decisions and has clear leadership (and I mean leadership not management). While it is not vital the leader be a blogger, it is nice to me if the leader leads by example and exemplifies the qualities they expect from others. If you look at the best blog networks they do tend to have decent bloggers at the helm and set the tone and standard for the others, the examples where this isn't true might point to future problems (mentioning no names) ...