Wikis provide a fantastic avenue for application of web 2.0 with students. I really like the possibilities for higher order thinking and evaluation skills which are required to genuinely assess the quality of material uploaded and shared.
Again, we have problems with access as so many spaces are blocked, but once set up, the students just love being able to share their information and thoughts.
I have found that they are far more likely to state their thoughts via this medium than to speak them aloud, in case they are 'wrong'.
I also see applications for using wikis in the library - just need more time to develop the ideas further.