The new Technorati, now in Beta, is a major step forward for blog search services. It pulls in data from flickr, furl, delicious. It ranks books, movies, blogs, and news stories by number of blog mentions. It highlights searches by tag (still thinking about tags).
Again, what impresses about the major open web-based services is how they make data work as hard as possible in support of the user experience, data which may come from a variety of places.