Well, I'm quite impressed. My sophomores are still updating their study hall page at http://studyhall.wikispaces.com/ and we're into day 4 with no requests nor grades from me.
They have also worked to create study notes for their biology test which they have linked to at http://studyhall.wikispaces.com/biology+notes+1-8.
This is the amazing thing I am noticing - these students really are collaborating! It is not just one student doing the updating. They are taking turns and working together!
Students who are weaker in the organizational skills are saying that this is a lifesaver! The other interesting thing happening is that students are inviting and training other students not in my computer science class. It will be interesting to see if there is a reflection in the class grades overall.
I have taught web design for four years but I have never seen a space evolve as quickly as these wikispaces. It is a great concept worth exploring more! Impressive so far! Very easy!