Thinking about the concept and practice of Community Wiki more often than not these past few days as come to a head: what exactly does TeX.SX believe about community wiki? What questions count, and what questions don't?
Reading The Future of Community Wiki has me thinking that community wiki should only be used when the content needs to be edited from time to time, like our LaTeX Editors and IDEs question. Similarly, something like How can I explain the meaning of LaTeX to my grandma? is not community wiki because it does not need to be edited often if at all. The question is applicable to the entire TeX community and, while each answer is valid, there is a best answer as far as OP was concerned - the answer that his grandmother supposedly understood.
As with anything, there are many ways to approach a problem. There isn't "one right answer" to anything, and this lack of a single answer is what drives many questions to CW which isn't the point. The recent question Showcase of optical illusions made with TeX/LaTeX/LuaTeX/ConTeXt is a perfect example of this; while there is no one right answer, the answers will not need to be edited. While the sum of the answers is a community effort, each individual answer is not.
I realize that we do things a little different around here and I think that's awesome. It's what makes us special and, frankly, a generally nicer environment than many other SE sites. We don't hound around for reputation, but are we to abuse what is designed to be a specific tool for great content?
@JosephWright reminded me that answers can be made CW by their posters. I think these are something of a nobler outlier---where the poster of the answer knows his or her answer isn't perfect but wishes it to be so. (I've done this, too.) So, I would like to concentrate this meta question on CW questions, rather than answers that are elected to be so.