Wikis for internal collaboration

The New York Times today has a brief interesting article about Diplopedia, the internal wiki developed and used by the US State Department. If the State Dept can successfully use a wiki to encourage modern collaboration among its employees, why don't more schools and universities embrace wikis as a tool to promote change, map curriculum, encourage professional development, model 21st century skills, strengthen missions and strategic plans, and, perhaps best of all, reduce the number of face-to-face meetings we all attend? 

Wikispaces makes it easy to add internal wikis to an organization using their Private Label service.