It went very well indeed. We've been doing some work on applications of maths to personal finance, (with spreadsheets for trial and improvement), so for the weekend HW, I asked them to find out and explain what a number of the technical terms meant, and post the results into a wiki I'd started.
Initially they were very worried about the possibility of vandalism, but the news that all changes were tracked and reversible reassured them. They got to it over the weekend, some obviously making more of a contribution than others, but the logs suggest that even those who joined in later looked through the majority of entries, with one pupil in particular choosing (without any prompting) to adopt the necessary house-keeping role and correcting everyone's spelling and punctuation. There was a strong sense of collaborative work that's largely been absent from the on-line quizzes.
Here's a post from the discussion forum:
I think the weekends work is a great idea!
We should do it more often!!
BTW, has anyone else experienced problems with HTML-editing wiki pages in Firefox? The screen flikers, and whilst I can save an initial entry, when I come back later it ignores subsequent changes I make. The problem disappears in IE or if I change the option to safe HTML, and use good old webforms. Firefox HTML editing works OK elsewhere.