Is Wikipedia just about done? My answer for you is no, despite what the statistical decline might lead you to believe.
For years, it seems that the online repository of information has had exponential growth. Now that this has slowed, people are starting to wonder why. I think that it is fairly obvious that those growth rates wouldn't continue, because there is only so much information in the world. A great deal of what people were interested in learning about and teaching others about has already been added to the site. As has been shown, the site is reliable enough and probably has more content than any other reference site out there (besides the internet at large). I think that the site will continue to be popular, and will be updated and maintained as necessary. This decline in growth is not, as a commenter on TechCrunch thinks (second comment after the post), a sign of the end of Web 2.0.
For me, the site will continue to be useful. While preparing for a recent presentation that I gave on RSS Feeds, I discovered that it is possible to subscribe to a Wiki page via RSS. This will let you know anytime updates are made to a particular page, and can be particularly useful for companies or people wanting to monitor what is being said about themselves or their products and services. To access this feature, click on the History tab in a Wiki page, and then in the toolbox on the right hand side there will be a link to the RSS feed.
During that same presentation, I asked the audience (about 40 people) if any of them used Wikipedia. Every single person raised their hand.
This made me think: With all this talk about Wikis, how many people actually use a wiki besides Wikipedia? I use one at work, and find it to be quite helpful for all of the obvious reasons (document collaboration, etc). But none of my friends use them at their jobs, and I haven't heard a lot of stories about the use of wikis catching on anywhere else.