There's a nice introductory article titled Wiki While You Work that was written by Mauro Cardarelli for TechNet Magazine. Mauro's article discusses the problem space and how you can take advantage of Microsoft Office Sharepoint Server (MOSS) 2007's WIKI functionality.
As the article explains, wiki's are not new but they don't seem to have hit the mainstream until very recently. MOSS provides the means to implement wikis within your organisation enabling users to easily collaborate and share ideas. An important feature of any wiki is the facility to review and even rollback changes - MOSS excels in this department.