I've been spending some time over at David Sifry's site (he runs Technorati). He's got some beautiful graphs that do exactly what graphs at their best do - marshall information in a clear way that makes intuitive sense.
Some of his observations: the blogosphere is doubling in size every 6 months, meaning that it's now over 60 times bigger than it was 3 years ago. So, in April 2006, 75,000 blogs were created a day. That's every day, people. About 3.9 million bloggers update their blogs at least weekly, and about 55% are still posting 3 months after their blogs are created. The rate of posting shows a similar steep upward trend, but doesn't appear to show the exponential growth that the size of the blogosphere does. Any predictions for the future? Continued exponential growth? Leveling off? Guesses welcome.
Sifry also found that the blogosphere is multilingual, and deeply international. If you check out the bar graph at bottom right, it shows that English isn't the biggest language of the blogosphere anymore. The plateau of the last few months is probably too short to project that language usage is stablizing. I'm curious to see how language trends will play out over the next few years.