I was actually surprised to read on the E-learning description that although Wikipedia allowed anyone to contribute is has a tight set of guidelines/rules and moderators that keep the information accurate and avoid breaches of copyright. I actually just had an idea in my head that you as the user needed to work out what was fact and fiction. Which is still the case to a certain degree but its is good to know that the information is monitored.
As a resource for your students I think Wikipedia would be an easy quick way to look up knowledge that they don't know or are not clear on. In the classroom I would use it to get students to research answers to questions or problems that they had rather than just telling them the answer. Wikipedia would allow students to engage in a learning activity that involved them using cognitive processes such as problem solving and evaluation to come up with a solution/answer (Kearsley & Shneiderman, 1999). Obviously time would be a factor and it could not be done all the time but when time allowed it I think it would be an excellent tool for students' to develop their research skills.
I actually used Wikipedia in my class a couple of weeks ago. We were reading a book about amphibian's and they asked me what it was. I actually was not to sure myself so we went over the computer and looked it up on Wikipedia. I looked through several sights but that was one of best as it explained it in easy direct terms. One of the students enjoyed the lesson that much she went home over the weekend and made a book about Amphibians. It was great to see that she really wanted to find out more about the topic! Plus she did a fantastic job of the book!
Kearsley, G & Shneiderman, B (1999). Engagment Theory: A framework for technology-based teaching and learning. Retrieved July 29, 2009, from CQUniversity e-courses, FAHE11001 Acitive learning & learning diversity.