In one of Google's lobby there is a 3-D animation of a spinning globe, with spikes that appear wherever and whenever searches are performed, with the height of the spikes being proportional to the rate of query submissions. The recruiter who showed me this was very proud of google's accomplishment and indeed it was impressive to see the spikes erupting from the east and west coast of the US, Europe, Japan and India.…
As for Africa, it is probably a case of not having gained a critical momentum for the kind of infrastructure the article talks about. This doesn't mean it won't happen - while we don't build CDNs at the place I work, we do build basic infrastructure for access control in wireless and mobile networks, and we are definitely seeing more activity and business from African regions compared to how it was earlier.