In other news this week IDPF released eBook sales statistics for January 2008. The statistics are limited to trade books and roughly a dozen publishers. The data does show an interesting trend line though. The site has links to other interesting e-book statistics as well. Here is the current graph, which you can also find on their site in a slightly larger format with a little more detailed trend data:
Notice the slope of the line. That is an improving trajectory. The volume is still low, but the trend is goinig in the expected direction.