It features a good historical introduction of the Free Software movement in general and discusses topics such as geeks, nerds, hacking etc. The main part is about the social aspects, though, especially motivation and commitment in the Free Software community.
The results of four interviews with famous Free Software developers are a major part of the thesis. There developers are:
I'm through half of the thesis now and really recommend reading it, as it gives some interesting insights into the social aspects of Free Software development.
(via Harald Welte's blog)