The Great American Novel Finally on Amazon?

In an otherwise uninteresting article about self-publishing, I came across this paragraph:

Publishing a book takes a year because everyone expects it to – not because it has to. Not surprisingly, Amazon is eyeing the self-publishing niche. The Web site has roughly 10% of the retail book market but nabbed 40% of Kessler’s sales. Big self-published books mean big market share.

Is this true? It’d be interesting to see what happens to POD if Amazon throws its hat in the ring.