I still find interesting the parallels and differences between the U.S. and Japan. The rate at which e-book sales are clmbing is the same in both countries (roughly fourfold since 2000), but the total amount in sales is much higher in Japan. Japan's market is dominated by young women, while the U.S. market is more evenly split, but slightly dominated by men... yet both countries see the largest increase in romance novels, primarily read by women.
Also, according to the
Economist, Japan experimented with selling existing best-sellers and noted print authors, then porn, with no success. The U.S. seems to be taking the same approach with existing authors and best-sellers, and having low-to-mediocre results.
To my knowledge, there is a porn market, certainly not mainstream, but obviously they aren't making enough money to attract anyone's attention yet. (I doubt they were included among the publishers contacted by the AAP for the IDPF statistics.)