SixApart’s Anil Dash puts his finger squarely on what makes blogs so different from previous attempts to package journalism for the Web:

When I first wrote up the idea that had been percolating in my mind for the microcontent client, the one element that kept popping up was “meme-sized chunks [are] the natural idiom of the Internet”. A post is that memetic chunk, exactly the size of one idea. Not coincidentally, a lot of emails are that size, as are a lot of instant messaging conversations.

That’s it exactly — it’s the ability to generate a stream of knowledge, categorized and archived automatically, that makes blogs such a compelling journalistic form. Just now I’ve pointed right back to an idea of Dash’s — not a page, but an idea (which happens to be represented as a page). By undertaking the blog format, bloggers are essentially providing a soft guarantee that their ideas will be addressable by URI, which makes them extremely linkable and hence very Google-friendly. (I call it a “soft guarantee” because it’s implicit in the format itself, not explicitly agreed to.) This is also why RSS/NotEcho/etc. are so important — they provide the first working example of a way that these ideas can be distributed other than through a Web page. As time goes on and the infrastructure becomes richer I imagine we’ll see more of these popping up.