Is Slashdot a blog?
I would call slashdot one of the earliest and most influential blogs, although the fact that they publish reader-submitted stories (not just comments on the stories) does set it apart a bit from most others. Nonetheless, the content is very bloggish. Wikipedia, OTOH, has very unbloggish content, for the most part (excepting the Talk pages and a handful of special pages, but these are none of them the focus of the site).
Perhaps the more interesting question is, is Perlmonks a blog? I mean, yes, the subject matter is technical, but surely there are blogs with highly technical subject matter (e.g., In The Pipeline is clearly a blog, and organic chemistry is every bit as technical as Perl, or at least would appear so to the layman), so I don't think that alone can exclude it.