I've been using wikis for a little over a year now. I find it a very useful tool for collaboration and sharing of information. It is also more 'sociable' than a blog, for you have many 'voices' contributing. I came across this educational blog that I immediately joined as they are doing many things along the same lines as my team at work http://teaching-with-technology.wikispaces.com/
Wikis are very useful within a community of learners, whether they be teachers, students or just a group with similar interests.
