The growth of weblogs has been a classic disruptive technology event, with adoption and traffic driven by individuals rather than corporations. Google has had a leading edge insight into this because of the objectivity of the PageRank algorithm in measuring the connectedness of the web. Weblogs are a powerful driver of the emergent ordering of websites that Google tracks - I was able to get my son's website to be the top result for both 'andrew marks' and 'funniest stories' on Google by mentioning it on my weblog and having it picked up by other webloggers who found it amusing.
The Weblogs and power laws paper I wrote makes clear how important the long tail of webloggers is to the number of links online - they have a census view of links at Google, and can see how big and important the tail really is, even though their business is showing others only the head.
Most other web traffic measurement sites are following pageviews, and not considering power law distributions, so they will show the high end bias I discussed in the power law paper.