In publishing, information tends to presented in one of two ways: layout-driven or content-driven.
Layout-driven design applies more to traditional magazine, newspaper, and book markets where the content is often trimmed and rearranged to meet the physical constraints of space.
Content-driven design applies to more general documentation, such as legal papers, technical manuals, etc., where space is less of a consideration, and the information itself is paramount. In these cases there tends to be an ongoing flow of text, and the space expands to accommodate the required content rather than restricting it.
Wikis are content-driven.
It seems that the best way for a wiki to develop is to adopt what I term an “open space” model; that is, let users post what they want, where they want, and let the structure develop itself. However, this approach is not without issues.
Where you have an open space wiki model you need someone, a wiki-maven, dedicated to maintaining and managing the wiki and its content. The most successful wikis adopt the open space model and develop active communities.