Technorati stats are showing that the number of blogs posted are doubling.
Posting volume has doubled this year alone - between January and August, in part due to the growing number of mainstream blogging tools such as MSN Spaces, AOL Journals, Blogger, and LiveJournal. At the end of July, about 37,500 posts were being created every hour.
Posting volume is likely a better measure of blog activity than the number of blogs being created, and a better indicator of whether blogging is just a fad or a sustained activity. -MarketingVox