Flurry provide a usage statistics service for smartphone applications, collecting data when the application is downloaded or used. As a result they have interesting data on the state of the smartphone market.
Eyecatching for me is the chart in the "Smartphone industry pulse July 2009" showing that customer use of eBooks is rising quickly and is second only to games:
The data probably underestimate the situation, as far from all eBooks will have Flurry embedded in them.
In another analysis "Mobile apps: Models, Money and Loyalty" Flurry have also looked at how frequently apps are used, and how likely users are to return to them after 90 days. That suggests that books are used intensely (maybe 10 times a week), but are not used much after 90 days. The customer has finished the book by then, presumably.
For the technically minded, Flurry describe the technical workings of their service thus:
Flurry Analytics places a lightweight agent into an application, so that performance data are tracked, logged and reported back for analysis. This information is confidential and available only to the developer to analyze in aggregate. Individual user data is not identifiable. Developers are provided a wealth of metrics around usage behavior, any custom event they choose to track and technical information about the device, firmware version, carrier and more.