Talking about the size of the blogosphere the key quote for me was "The number that I find indicative of the true growth of the blogosphere is the number of daily posts. That is a much better way of being able to watch how much time people in aggregate are putting into writing on their blogs. Today we’re tracking about 1.2m posts a day. A year ago it was a third of that."
This figure is more interesting than the often cited total number of blogs (27m at the last count) because it discounts the 50% of new bloggers who give up after three months. However, it’s still far from perfect as it doesn’t discount the splogs (spam blogs) which are frequently simply made up of aggregated content surrounded by adverts.