Wikipedia:CamelCase and Wikipedia
When Wikipedia was founded on January 15, 2001, it used the wiki engine UseModWiki, which only supported CamelCase links at that time. However, on February 19, 2001, Wikipedia enabled and recommended free links.
A year later, with the introduction of the Phase II software in January 2002, support for the automatic linking of CamelCase links was dropped altogether, and an automated conversion script was run to convert CamelCase names to new-style names, although by this time almost all CamelCase links in articles had been removed anyway.
CamelCase can still be found in the non-encyclopedia parts of Wikipedia, such as Talk pages, where the links have not been updated. Many Wikipedians have CamelCased user names, either as a leftover from the early days, carried over from other wikis, or simply because they choose to use them.
I've done a lot of thinking about WikiLinking recently, and I'm not sure that the WikiName (capital letters) convention is a good fit for the encyclopedia. The AccidentalLinking is a nice feature, but it has a price in harder-to-read links and confusing conventions.
For instance, when I recently wanted to link to "democracy", I first did a search to see if someone else had linked the name (I thought someone might have already used "DemoCracy"). I found that nobody else had linked that name, so I made the link "DemocracY" (to follow the new convention of last-letter-capitalized). In short, it took me far more time to make that link than it would have to just type [[democracy]]. Someone unfamiliar with the local wiki conventions might guess otherwise on another page and link to a separate "DemoCracy" or even "DeMocracy". Ick.
To make a longish story short, I added code (about 150 new lines of Perl) to my development copy to allow (site-optional) "Free" linking within [[double brackets]]. You can use spaces, numbers, commas, dashes, and the period character in these kinds of links. Valid link names include [[George W. Bush]], [[China-Soviet Relations]], [[Physics]], [[music]], and [[Year 2000 bug]]. User names can also use these new links. Internally and within URLs the spaces are replaced with _ (underline) characters, which are translated back to spaces for display purposes.