I recently created a wiki with another teacher on the topic of using blogs for reflective learning. It was a interesting and rewarding process. The biggest difficulty was getting started- determining our topic, content of the topic, and what sections to write about as a part of the overall topic. I was not very familiar with the topic initially, though I did have some of my own ideas on how to use blogs for reflective learning. Once I researched the topic and found some websites that explained it, the topic was very easy to write about in our wiki. I learned a few things from this project- namely, the actual topic of how to use blogs for reflective learning. I gained some new, great ideas on how to incorporate this into my classroom. I also learned the ins and outs of wiki creation. I have previously contributed to a wiki but it was a simple typing in of some info, not as in-depth of using and making a wiki.
My opinion of Wikipedia has changed some this week. While it is more reliable now than maybe several years ago when misinformation was not updated quickly like it is now, it is still not a resource that I would want my students to use for a formal, research paper or project. But it is a great source to look up quick information.
I so far am not encountering resistance to using wikis in my classroom. I think students would enjoy using wikis, once they were taught the ground rules from me for their appropriate use. I will need to determine how to best incorporate wikis in my online classes.