Google adds blog search, using the tag line "Find blogs on your favorite topics". According to the help page, Your results include all blogs, not just those published through Blogger; our blog index is continually updated, so you'll always get the most accurate and up-to-date results; and you can search not just for blogs written in English, but in French, Italian, German, Spanish, Chinese, Korean, Japanese, Brazilian Portuguese and other languages as well.
It is live (but in beta) at http://blogsearch.google.com/.