Luminos is a new initiative from the University of California Press (H/T The Scientist). Its focus will be on scholarly monographs (book-length projects), and costs would be shared between the author(s), the University of California Press, and libraries who opt (voluntarily) to subscribe to Luminos. These contributions would help populate an Author Waiver Fund to help defray costs for authors.
Works published by Luminos would be available for re-use under a Creative Commons license (the Press would prefer CC-BY, but is open to alternatives). Print copies would also be available, but digital or digital-to-print copies would be the main mode of distribution.
Luminos is one of two initiatives of the University of California Open Press. The other program is Collabra (which I had erroneously identified as a U.K. effort). Collabra is an open access journal, which is experimenting with paying peer reviewers. Part of the article processing charges will go back into the funds used to defray participation costs and pay peer reviewers and editors. The value added with Collabra is arguably how it engages with the value of its product. Besides the payments for editors and reviewers, the journal provides the option of open peer review and post-publication review.