Turning large documents into a wiki

My physics department has a departmental handbook, which describes how the department is organized, what its aims are, details of the department's policies and practices, and so on. Maintaining the handbook presents a lot of problems. We try to ensure different members of the department complete different parts, but it is very difficult to collate these when they have been written. How can we make ownership of this document truly collective? The task of putting together our handbook, as well as all the other documentation we need, often detracts us from doing our actual job (teaching!—but that's sometimes difficult to remember given all the other things we are expected to do). How do we show the subject inspector that we are really working together as a team creating our departmental documentation?

An elegant solution is to turn departmental documentation into a wiki. "Wiki" is Hawaiian for quick (see http://en.wikipedia.org/wiki/Wiki), and a wiki is a...