Wikiwhat?

So now on to wikis... Personally I was always against letting students use wikis for research in the past. Why you say? Because I thought ther'e would be issues with false information and hearsay. On the flip side though, wikis are quick and information can be posted with lightning speed, unlike the good old encyclopedia. I am going to be doing a unit soon that requires students to do some research. Should I allow the use of wikipedia? Should I not? What do you all think? Maybe allow wikipedia but tell students they must find that same information elsewhere as well to "back up the facts"? Still leary but it's technology so I have to go there! :)