He has profiled several organizations using wikis (including my favorite, the Westwood wikispace that I manage.)
He begins with an excellent profile of a worthy organization, Never Again International. This organization is a a nonprofit network dedicated to promoting peace and preventing genocide, and uses a wiki to share information around the world.
Brian does a good job of profiling the various types of wiki environments and choices and it is a good jumping off point for anyone who is ready to get started with wikis.
In addition to profiling Never Again International and the Westwood Wiki, there is an interesting profile of Client Access to Integrated Services and Information (CAISI) — a Canadian nonprofit working to build software that helps homeless shelters, advocacy agencies, and hospitals to integrate their databases — has found a wiki to be a fast and user-friendly tool for documenting the project's development and making information freely available to the open-source community.
If you have an interest in wikis, this is must read article for you!