The history and operational details of the Madison project are described in depth in the MIT dissertation.
Here’s the official web site for the project. It includes full information about the current operation along with site plan and photos.
The MIT dissertation located at http://dusp.mit.edu/sites/dusp.mit.edu/files/attachments/news/mingoya_2015.pdf is one of the most complete resources available.
Catherine Mingoya wrote this for her dissertation in urban planning and examines in depth the mini-houses projects in Madison Wisconsin and Portland Oregon — two very different projects with unique histories and challenges.
While long (89 pages), it offers one of the most complete case studies available online.