OAPEN (Open Access Publishing in European Networks) has released Overview of Open Access Models for eBooks in the Humanities and Social Sciences. From the summary:
This research has looked at a variety of initiatives and specifically at their publishing models, business models and publishing processes. Within these divisions, special attention has been paid to the nature of the content, the level of Open Access provided, the peer review and copyright policies and, finally, the strategies of collaboration. The Open Access book publishing initiatives analyzed in this report have been classified according to their publishing models, they have thus been categorized into commercial publishers, presses established by societies or academies, presses established by libraries, library-university collaborations, university presses, presses established by academics and press-commercial publisher partnerships.
The SPARC-ACRL forum held at the American Library Association Midwinter Meeting in Jan. 2010 addressed the "collaborations and innovations behind open-access monographs." The videos of the presentations are available online.