There are lots of blog search services around. It will be interesting to see how they consolidate, and what emerges as preferred functionality.
I have ego feeds set up with several and in my experience none does significantly better than others, although I don't watch it closely. Blogpulse, Technorati, PubSub, Icerocket and Feedster will occasionally throw up a result the others don't have.
In fact, my impression, not tested, is that Google's Blogsearch gives the best overall coverage.
That said, it provides a 'flat search' - it does not allow you to follow the 'big-assed threaded conversation' that blogging is. For that reason, I find that I will look at it in addition to, not instead of, Technorati.
Newer services are appearing - testament to the importance of the blog. Blogniscient categorizes and ranks blogs and incorporates Google's Blogsearch. Sphere is a new blog search tool in beta, which claims to return results by relevance.
Some services allow you to search for blogs among other results. Yahoo News is one, though I have not used it much as I did not seem to me to give as good results as others when I looked at it. Rollyo allows you to 'roll your own' search by nominating groups of sites - potentially including blogs - to search together. A variety of celebrity searches are available. It doesn't have the critical mass to mean that I use it.
Given all that, I find the most interesting recent development to be the new search capacity on del.icio.us. It allows navigation within the aggregate personal choices of its users - in terms of tags and links. And in fact, as I used it, it struck me that following tags is like conversation in some ways: in each case, you get hints and pointers, you fork in different directions, you are at the intersection of a variety of interests, and you are woven into a fabric of reference which may have more or less to do with the world outside the conversation.
If del.icio.us search were to have greater mass it would be a compelling service!