Great observation, Don. Thanks! I think you're on to something very important here. e-books make it easy and inexpensive to distribute materials for sure, and there does seem to be a growing appetite among educators to write material and share it for little or no return. I think academics are coming to understand that the real incentive for writing material is to reach an audience, and traditional publishing outlets such as subscription-based scholarly journals and academic publishing houses are not the most effective way to reach a wider audience with material. Of course there is still the institutional attention paid to conventional academic publishing, especially when considering tenure and promotion, but those walls are being chipped away little by little.
My own experience has been that my free ebook outperformed any previous book I had ever written, and it did it in less than three months. And now I see the classic long tail of e-distribution stretching out behind the initial burst of downloads. I really like Google Analytics, and it provides some of the data we need to be able to document the performance of publications.
Here's something I've been wondering about, though. Because ebooks require some kind of technology to read them, is there an equity problem? For people who can't afford or don't have access to readers, laptops, notebooks, etc., are they being systematically excluded from learning opportunities? Maybe this is where things like e-reader loaner programs from public libraries become even more important.