E-read had a good piece recently asking the question, are PODs ebooks? With more stores and libraries engaging in print-on-demand (POD) activity, there may be some interest in the perspective and few data points presented.
The piece has a good contrast and comparison between offset printing (characterized as an approach of the past) and POD (characterized as an approach for the future). And it includes links to a two part discussion on "a future without inventory" that is also worth reading. (See Part 1 and Part 2).