The project coordinator is generally responsible for maintaining all of the procedural and administrative aspects of the project, and serves as the designated point-of-contact for procedural issues. She/he is not, however, endowed with any special executive powers and nor does her/his opinion carry any greater authority than that of any other editor.
The primary responsibility of the project coordinator is the maintenance and housekeeping work involved in keeping the project and its internal processes running smoothly; this includes a variety of tasks, such as keeping the announcement and open task lists updated, overseeing the assessment and review processes, managing the proposal and creation of work groups, and so forth. There is fairly little involved that couldn't theoretically be done by any other editor but as often as people tend to assume that someone else is doing whatever needs to be done, it has proven beneficial in other projects to formally delegate responsibility for this administrative work to a specified person or group.
The coordinator also has several additional roles. She/he serves as the project's designated point of contact, and is explicitly listed as someone to whom questions can be directed in a variety of places around the project. In addition, she/he has a (highly informal) role in: leading the drafting of project guidelines; overseeing the implementation of project decisions on issues like category schemes and template use; and helping to resolve disputes (as mediator not arbitrator) to keep discussions from becoming heated and unproductive.
Any other editor is welcome to take on these roles as they desire: the coordinator is simply there to ensure that such tasks are done.
If there is more than one person wishing to be the project coordinator, an election by a simple approval vote of all project members will be held. Every six months confirmation will be sought as to whether anyone is interested in replacing the current coordinator. Any member of the project may be a candidate; this includes the current coordinator, who may be re-elected without limit. The coordinator may resign at any time, which prompts this selection process to fill the coordinator position for the remainder of the six-month term.