Role of Moderator

What is this role of "moderator" and what does a moderator do in the Presbyterian Church (U.S.A.)?

The official description:

When the Moderator presides at the assembly, it is to be "a sign of the bond of unity, community, and mission in the life of the church."  Between assemblies, the Moderator serves as an "ambassador of the unity of the Spirit in the bonds of peace, telling the story of the church's life and upholding the people of God through prayer.  The Moderator of the General Assembly is an "ecclesiastical officer" of the Presbyterian Church (U.S.A.), possessing "the authority necessary for preserving order and for conducting efficiently the business of the governing body."

Specifically, the Moderator of the 220th General Assembly has at least three significant responsibilities:
  1. Moderate and provide leadership and order for the General Assembly meeting of the Church, which is held every two years
  2. Travel as ambassador for Christ and the Church, teaching, speaking, praying, and encouraging this part of the body of Christ that is the Presbyterian Church (U.S.A.), and sometimes representing that body to other parts of the broader Church
  3. Appoint members of special committees and task forces created by the electing General Assembly (220th), and appoint chairs to General Assembly committees at the subsequent assembly (221st)

If you really, really want to know a lot more about the role, you can view the Moderatorial Candidates' Handbook from the last General Assembly (2010).  It's 66 pages in length and includes a description of the process for election, some official questions posed to the candidates in 2010, and the bio packets from each of the moderator and vice-moderator candidates.