Dave Winer, one of the leading lights in the blogosphere, has a piece asking what makes a weblog a weblog? It's an interesting piece because in addition to giving a good introduction to the different parts of blogs, he demonstrates what I think is a basic confusion over defining blogs: is it a technical thing, or is it a social one?
At one point he favors a pretty narrowly technical answer: "A weblog is a hierarchy of text, images, media objects and data, arranged chronologically, that can be viewed in an HTML browser."
But he also decides that a BBC blog, which doesn't have the technical features that he considers blog-defining, is ALSO a blog, because its contributors
are writing about their own experience. And if there's editing it hasn't interfered with the style of the writing. The personalities of the writers come through. That is the essential element of weblog writing, and almost all the other elements can be missing, and the rules can be violated, imho, as long as the voice of a person comes through, it's a weblog.
This confusion is a nice example of the problem we have whenever we try to define a technology: can a complete description rest with its formal specs, or does it also have to consider use and context? Of course, I come down in favor of what's behind door number two, but the choice means you have to work pretty hard to arrive at something that's meaningful and useful.