According to the 'State of the Blogsphere' statistics released by Technorati, around 80,000 new blogs are created daily - at least one every second. Of the 14.2m blogs tracked, 55% are considered active (a posting in the last 3 months) and 13% are updated at least weekly.
More State Of The Blogosphere
Technorati have posted more stats about the blogosphere such as:
* Technorati is tracking about 900,000 blog posts created every day
* That's about 10.4 blog posts per second, on average
* Weekends tend to be slower posting days by about 5-10% of the weekly averages
* During the day, posting tends to peak between the hours of 7AM and noon Pacific time (10AM - 3PM Eastern time)