The latest issue of the Journal of Electronic Publishing includes the article "Toward the Design of an Open Monograph Press" by John Willinsky.

Abstract:
This paper reviews and addresses the critical issues currently confronting monograph publishing as a matter of reduced opportunities for scholars to pursue book-length projects. In response, it proposes an alternative approach to monograph publishing based on a modular design for an online system that would foster, manage, and publish monographs in digital and print forms using open source software developments, drawn from journal publishing, and social networking technologies that might contribute to not only to the sustainability of monograph publishing but to the quality of the resulting books.

You can find out more about OMP here.