To our knowledge, ListenLog is the first open source activity logging (or tracking) application intended to work as a tool for users, in which the data generated is under the control of users.
There are two goals for ListenLog. One is to help establish self-tracking as an independent and autonomous activity by and for individuals rather than a grace of commercial enterprises (e.g. FourSquare, Zeo, Withings), for which user's access to the data they generate is controlled by those companies (and in some cases considered those companies property and a corporate asset), rather than by the users themselves.
In this first incarnation, ListenLog will track listening to Public Radio Player (which has had more than 2.5 million downloads so far), and can be viewed through browsers (both within the Player and on the user's own computers).
Bear in mind that ListenLog is not meant to be for the iPhone alone. We can think of many generative ways it can be put to use on Android, Symbian and other platforms that are free from the restrictions of Apple's feudal market-containment system. Also, there is nothing to prevent ListenLog from being social as well (for example, allowing users to tell others what they are listening to). So we see the current version as the first of many steps.