WHAT!?! - This is almost so last century. Wikis on there own are no longer innovative. This said, Wikis are great collaborative tools and personally I prefer to capture content in a Wiki than in a blog. I am constantly fascinated as to the breadth, scope and overall accuracy of Wikipedia. It is on of the great information innovations of the last few years.
Wikis seem much better for information that has a longer life cycle or where it is important to capture point in time changes. Blogs on the other hand seem to work best when capturing discussions and ruminations. However, many of the Wiki wysiwyg editors leave a lot to be desired so an understanding of html remains a good skill to have. I guess it is a bit like cars in that having a basic understanding of motor mechanics is handy skill but not an essential skill when driving a car. Then again considering how some people drive I might have to contradict myself.
There are some very interesting Web 3.0 and Semantic Web projects which are using wikis. See the Tetherless World Wiki and the SemanticWeb.org wikis for details.