Here's the breakdown via Joanne McNeil:
Not Blogs: pre-2002: Geek notes, diaries, frequently updated zines. Things that looked like blogs but went by other names
Linkblogs: 1999 (2011?): Perhaps even earlier than 1999. Linkblogs were either quick links or a blockquote and a link. Nothing labor intensive about sharing cool stuff but some people have better taste than others. Are they dying? Maybe? Twitter seems to have taken over for directions on how to get lost online
Warblogs: 2001 2004: You know how everyone has something to say about Wikileaks? Imagine that times twenty and that was the post-9/11 blogosphere. Here’s all you need to know about this frenzied media landscape.
Post-Diaries: 2003-2005: Pre-Facebook, although concurrent with Friendster and Myspace. Years before we had any kind of meaningful public vs private discussion as the sense was, with so much out there on the web, who is going to pay any attention to me? The post-diarists used their blogspot pages as nascent social networks, a way to reach multiple close friends. You probably knew all your best friends’ IP addresses because Sitemeter never clocked more than ten visits a day.
Movable C.V.s: 2004 2008: Blogs went niche. If you called your blog “Vegan Buddhist Goddess Blog” then CNN and NPR would call for comment if they were doing a story on vegan cooking. You’d be invited to speak on panels, maybe get a book deal. In any case, a blog was a way to establish yourself as a leader in your field.
Mainstream Media Blogs: 2007 current: Apart from the New York Times and The Atlantic, many of these blogs are unremarkable. And readership reflects this. Whenever I go to a newspaper website I’m always surprised at how many in-house blogs exist, but few seem to attract more than a hundred or so RSS subscribers.
First Draft Essays: 2008 current: Now blogging is the habit of those who love the sound of their own fingers banging away on a keyboard.
There are interesting extended thoughts in the rest of her post. I loved this:
This reminds me of what Hannah Arendt wrote of Walter Benjamin, that he was a “critic and essayist who regarded even the essay form as too vulgarly extensive and would have preferred the aphorism if he had not been paid by the line.”