There have been a variety of discussions on meta about Official Positions [OP]; some of them recent. See http://meta.wikimedia.org/wiki/Official_position http://meta.wikimedia.org/wiki/Board_agenda/Open_questions_2#Positions
This is one of the major elements of discussion at today's Board meeting.
I would like to present a somewhat contra-OP argument that the core of WP's success has not been its exclusive delegation of responsibility to individuals, but rather its successful empowerment of /all/ of its users, even new ones, to jump in and do what needs to be done. Providing Officers with unique power and authority is a two-edged sword; it encourages those individuals to take extra responsibility, and provides them with authority to herd other volunteers. But simply going out and working diligently on a project provides a similar authority, and an internal, rather than an external, sense of responsibility.
The existence of rare, Board-sanctioned official positions in areas where there is not already an active group of un-official Wikipedians, can discourage the rest of the community from jumping in, and adds heirarchy and single points of failure to what would otherwise (in the case of a pressing event) be an open system.
I would be comfortable with the creation of special interest groups based around the priorities of the community and the foundation, before deciding on individuals to represent those interests. Creating titled individuals to carve out new interest groups, as has been suggested in the past, is certainly unwiki and probably unscalable.