The results of searching blog posts, tags or for entire blogs are quite different, although they can also delivery some of the same results depending on the content of the blog and how they've been tagged. For example, there were some blogs which turned up in the search for blog posts and tags. It seems to me that searching for tags or entire blogs might turn up more useful results if you want something specific, but if you want to do as wide a search as possible searching the blog posts might be the way to go. It's interesting seeing what is popular too as a way perhaps of getting into a bunch of blogs without having to do too much searching.