Wikis constitute excellent tools for documentation and communication, two critical aspects of project management. The biggest advantage is its open nature which allows the project manager to structure or format the tool as required.
Next to the hugely popular Microsoft Project, Wiki is arguably the most helpful tool for the project manager. Wikis may not be able to substitute for MS Project, but both complement the other in many ways. A Wiki document, for instance finds use as a communication tool by providing the PDF or JPG narrations of the current project plan to team members or even to customers, and becomes especially handy as not everybody will have MS Project installed.
The benefits that Wiki provides notwithstanding, using Wiki successfully requires much self-discipline from each individual user. Even one team member doing the wrong thing such as deleting an important update can wreak havoc. Again, open sourced Wikis do not have built-in easily updatable views for Gantt charts and graphical overviews. Another disadvantage is that using a Wiki requires connectivity to the Internet or access to the network where the Wiki is installed; and this may not be always available.