I have used a wiki in another class called AsUlearn by appalachian.  It was pretty easy to use.  We used it to post information about books we were reading and give input on what was going on in the class.  The wiki we used in here was very easy too because we did not have to learn how to set up the writing.  We just copy pasted and changed the information.  I have never used a wiki in my classroom and would be anxious to see how I could use them.