I found these statistics on a link from the Feed Burner Page.

Over 12 million American adults currently maintain a blog.
More than 147 million Americans use the Internet.
Over 57 million Americns read blogs.
1.7 million American adults list making money as one of the reasons they blog.
89% of companies surveyed say they think blogs will be more important in the next five years.
9% of internet users say they have created blogs .
6% of the entire US adult population has created a blog .
Technorati is currently tracking over 70 million blogs .
over 120 thousand blogs are created every day .
There are over 1.4 million new blog posts every day .
22 of the 100 most popular websites in the world are blogs .
120,000 new blogs are created every day .
37% of blog readers began reading blogs in 2005 or 2006 .
51% of blog readers shop online .
Blog readers average 23 hours online each week .