It’s a neat graph, but the story changes when you click the “absolute” link above the graph. Looking at the default format, relative values, one gets an inflated sense of the effect of iPod sales. This problem is compounded by the fact that the iPod data are cumulative, unlike the rest. I guess it has to be accounted for that one iPod can hold many albums, but I’m not sure this is the way.
Separately, what about non-iPod digital music players?
Still, interesting stuff, and worth a nod to Swivel anyway.