Dave Sifry of Technorati has an interesting analysis of the current dynamics in the Blogosphere:
Technorati was tracking over 14.2 Million weblogs, and over 1.3 billion links in July 2005
The blogosphere continues to double about every 5.5 months
A new blog is created about every second, there are over 80,000 created daily
About 55% of all blogs are active, and that has remained a consistent statistic for at least a year
About 13% of all blogs are updated at least weekly" (from Sifry's Alerts)"
Read the whole thing for lots of other interesting tidbits!