I agree with bluepapercup and michelel72 (hi!) that there is a difference between "blog" and "online journal". I see blogs as being more oriented toward "let me tell you about the world that we both share" and journals being more oriented toward "let me tell you about my own life". But it's a fuzzy distinction: dooce, for example, is often counted as a blog.

What really annoys me is the word "blogosphere", because it implies a shared culture among blogs (broadly or narrowly defined) that just doesn't exist. (Unless you count most-recent-on-top dated entries, two- or three-column layouts, and intemperate language as a "shared culture".) I much prefer Max Sawicky's use of "Blogistan" to refer to the right-wing political blogs and "Blogovia" to refer to the left-wing ones.