Looks like I am an econo-geezer.
As far as the oldest blog goes, it seems like ArgMax has genuine posts going back to 1997, although they could be articles reposted to the blog, it’s hard to tell. Anyway, this graph shows the trend of the starting month for the 140 blogs in my list. Around 2004 seems like when economics blogging really took off.
For the record, the oldest of the posts on this site (going back over 10 years(!) from May 1997) were written as a weekly or bi-weekly online posting at About.com. At the time, there were not really things called “Blogs”, but there were a scattering of online journals and the like (Wikipedia says the term “weblog” was created in December of 1997, adn “blog” in early 1999.) My postings at my previous site would probably be called a blog today. Argmax.com as a separate stand-alone site was started in early 2002 with a variety of services including a continuation of my regular (and irregular) postings.
Thinking back to 1997, I can’t remember if there were other economists who were posting short articles online on a regular basis (though Krugman had a monthly column in Slate starting around that time). And there was little discussion/referrals across websites as there is now (though there were discussion boards, listservs, etc). So, if you consider my earlier stuff a “blog” I suppose I could be the oldest.