Dave at Technorati does his periodic review of blogs.  There seem to be two big points:

1. the number of blogs (56K) is more than doubled by splogs – spam blogs
2. 4K, or 13.1% of real blogs are considered very high authority (500+ blogs linking in last 6 months)

While there another 26K blogs considered high authority (100 – 500 blogs linking in last 6 months), this remains a big number, and the law of averages, plus point number 1. above, suggests there are spam blogs polluting that number.

So I think we don’t want to prematurely jump to conclusions, but I liked the context setting at Cymfony.

For context there are about 13,000 radio stations, 9,000 TV stations, and 17,000 magazines in the US. (source: Forrester Research, “Left Brain Marketing“)