Questions on the Use of Wikis in Business

I have been thinking a little more about the use of wikis in a business environment and reading fellow students' posts on this subject. It seems to me that this venue could be very useful for coordinating projects. In my job, I juggle numerous projects at any given time and each project involves a different set of team members. I can see where one wiki might be used for coordinating multiple projects if all the projects had the same team members. However, I am trying to figure out if it is possible to have one wiki site for multiple projects, each having different project teams. Can individual collaborators be added to specific projects rather than granting all collaborators access to all projects?