How can wikis be used with students?

I can see wikis being used with students in a variety of ways. Being a primary teacher, my initial thought is that a wiki would be a great way to organize websites for students to use when conducting research. As we all know, it is a bad idea for students to freely surf the internet, and a wiki could provide a young student with several reputable websites to choose from. Here is an example of using a wiki site to organize websites, expectations, and research questions for a research project completed in the primary grades.

My concern about students editing wiki pages is that there is no way to monitor what students are writing. The information that students write will be instantly posted to the internet as soon as they decide to publish. I see this instant posting as a major downfall to using wikis with students. I would love to see an education-based wiki site created that would allow student revisions to be reviewed by the teacher before being published to the internet. I know that www.edublogs.com provides educators with the opportunity to preview blog responses before being posted to the internet, but I wonder if there is a wiki site that allows the same. If the teacher was able to review revisions before posting them, I can see wikis being used for students to post responses to research questions.