Jon Udell has some interesting comments about blog becoming an official term in the English language.
Just as telephones are meaningful only when connected to the telephone network, so blogs are meaningful only when connected to the blog network. Both are carriers of human communication, but where the telephone network is essentially fixed -- at least for now, until VoIP softens its structure -- the blog network is malleable and is shaped by our use of it. It's more like a nervous system than a computer network, and for good reason.
Blog and telephone are two examples of definitions that don't have much value when described technically or as they appear. Their real value comes when people use them and when the infrastructure behind the object creates value for the users (context is here). The interest and value with blogs is that they help create and highlight networks of people, much further than you can discover from reading the dry definitions.