Mitch Kapor: Deleting Spam Coments
My newest job is routinely checking for and deleting spam comments from the blog. It's a weird kind of spam -- innocuous but off-topic comments with a fake email address and a commercial URL (free trial for DVD rentals, for instance). Gosh, this is annoying. I'm getting two or three a week now.
See also this from Steve Johnson this subject. It appears some of these comments are also unibited attempts to leverage the target blogs PageRank in google."