I think you bring up a very interesting point in your discussion of forums vs. wikis. The idea of purpose often seems to be lost when dealing with web-served info. Info is a means to an end (usually research) but rarely is it purposive. It seems like meta-design is an attempt to address "purpose". "What would it look like for the web to be organized by what people are really trying to do rather than by the information they use in trying to get things done?" (www.metalaureate.com/blog)