The IT office where I work uses wikis to keep track of their work processes. My office doesn't use them, so I have limited experience with them, but can see how they would be very useful in a different way from that of blogs.
While blogs provide a good way to promote events, announce news, and get the word out about things going on, wikis are a more stable, but still easily up-dateable, kind of resource.
Rather than have to make changes in policy manuals or personnel guidelines, say, which then need to be distributed to the people who need to use them, these changes could instead be made on a central site where anyone who needed to could always access them, knowing that the most recent copy would be there.
Wikis could be useful in libraries both privately for staff, who might keep track of job responsibilities and workflow processes, and publicly for users, who could access FAQ sheets, information about library policies, etc.
The ease of use means that limited special training is needed for staff to participate in updates and ensure a current version, and the many templates and backgrounds available mean that wikis can match well with a variety of needs.
