I wish I could have had a few more minutes to think this through. When I was talking about Wikispaces at the conference someone mentioned the problem of students sometimes deleting the work of others. One of my presenter partners mentioned that Google Docs was more effective in that regard, which I think is possibly true. My response was that it was good that at least all information can be recovered with earlier versions. I also mentioned that for in-class group work (where I think the problem is most likely to occur) someone can be designated the person to do the input.
I should have gone further with that. That solution will work if students are simply gathering together their own ideas. But if they are all doing research and trying to post links or upload photos or copy and paste, each student needs to have access to the page.
But here's the thing. It's one thing for a group of students to be sitting together but each doing her own thing, oblivious to what the rest of the group is doing. That's not collaboration, is it? The students need to be talking to each other. They need to be making decisions about who will find what, discussing results, commenting on each other's finds, shaping the page together. If they are talking to each other, it's not a big deal to take turns posting so as not to override others' work.Then, I think, Wikispaces will probably work okay.