The first thing I would add is that I’m personally not convinced wikis will ever make it out of the trough of disillusionment (although for me I never had a peak of expectations!) . Wikis are too difficult for most people to use both technically and conceptually. The technical aspects they might solve, but I’m convinced they will crack conceptually.
The second is that it is too US centric. My experience in the UK is that corporate blogs aren’t yet slipping down, the problem is that they are still very much at the peak of inflated expectations and that some people need to take a reality check.