By this rule, I would think that "wikipedia"
(small letters) should refer to
any of various language wikipedias (e.g.
de.wikipedia.org and
zh.wikipedia.org), whereas "Wikipedia" (capitalized) should refer to the big
mama that comprises all the daughter wikipedias (the Wikipedia should be
www.wikipedia.org, though that link automatically points to the wikipedia at
en.wikipedia.org, I guess because that one was the first, and is the largest
and the most visited).
Wikipedia is a multilingual project which comprises *all* Wikipedias. If
you speak of "the" Wikipedia, you are including all language subprojects.
-- brion vibber (brion @