I'll be honest that I've had mixed feelings about wikis in general. I think at its heart it is a useful and quick way to change or edit web content by a variety of users. This could be handy as was seen in a few examples for libraries that wanted up-to-date online resources for things like subject guides or book reviews or even just general library index of terms where many staff and potentially even patrons could add or edit content.
The problem with wikis (especially on a large scale like wikipedia) comes back to control and citations. When there are constant free-flowing changes to content and numerous people can edit or change the information, how do you know who wrote what and whether the "source" is credible? In a way wikis are helpful in showing the strengths and weaknesses of the online age of constant change and updates. Wikis make the most of allowing free-flowing information and access, yet the ability to cite and control the content becomes even more and more difficult.