As of today, my feed readership is between 550 and 600. My Technorati authority is 117, my rank is 54,800ish. All things considered, my blogs are small, very much personal.
Yet, do the math. 100 MILLION blogs, and mine is the 50,000th largest in the world?
Or do your own test. create an empty blog, register it with technorati, post a couple of test messages, and do nothing else. Don't advertise it, don't point to it, don't create content. you'll likely find that Technorati will throw it somewhere around 1mm in authority.
He goes on to challenge Technorati's count of 100 million blogs because of this. What is really going on? Well, links to blogs follow a Long Tail distribution. You can debate whether it's a power law or an exponential, but it isn't a gaussian. Here's a 2005 links vs rank log chart, and here's a 2006 one (if Technorati want to run my old script that generates these we could have a 2007 one). Technorati's 'Authority' is the number of inbound links in the last 180 days. So, as Chuq notes, if you have a new blog with no links to it, it is ranked about 4 millionth, tied with every other blog with no inbound links. So yes, everyone is above average - they're all on the 96th percentile.
But what happens when you start getting links? I have a couple of old blogs that have a few. With 2 links, my rank goes up to 2.6 Millionth; with 3 to 1.9 millionth, with 5 to 1.2 millionth, up to this blog with 141 inbound links ranked at 44,734. This is a very easy hill to climb in percentage terms, though clearly getting into the top 100 is still relatively hard.
So what of Chuq's contention that the other 96 million blogs with no links are "abandoned, stillborn, or some kind of spam blog" ? A lot of blogs are made for specific events, and don't need further posts adding (and so may not have been linked to in the last 180 days), and a lot have a low posting rate, sure. But, as Dave Winer once said, by that measure every book and magazine article is abandoned. Not all blogs are interested in links - many are personal journals or for a small group of friends to read, and achieving those goals well.
So Chuq's accusations of "playing fast and loose wiht the numbers" are really his misunderstandings of Long Tail distributions. In the Blogosphere, like Lake Woebegon, everyone really is above average.