Brett Simmons at inessential.com observes that weblogs are ten years old. Two commentators point out even older examples, including the first web site: info.cern.ch. This led me to the follow observations.
Blogs are just a continuation of an Online/Internet tradition that can be traced back to bulletin board systems (BBSs) and newsgroups.
If one wishes to draw distinctions, I would distinguish the beginning of blogging with the first "popular" blog-specific software tool. Any claims as to which tool that is?
IMO the essence of blogging is in one's approach to creating blog content, not whether the content is chronologically ordered. Otherwise, any website with a list of chronological events qualifies as a blog.
What distinguishes blogging from web site development generally is its emphasis on generating periodic (daily) observational/commentary content with minimial technical knowledge required. Thus, the mere fact that someone posted her observations to her web site on a daily basis, still wouldn't fit the paradigm of blogging, if she used general purpose web site development tools to do so.
What has made blogging the mass market phenonomenon that it is, is the non-technical ease of use of its tools.