From the FAQ used to inform discussions before adoption of the policy

• No. The faculty at Harvard University, as well as at Stanford, MIT, Boston University and others have adopted similar policies. The language in this document draws heavily from similar policies adopted over the past two years by these institutions.
• Research funders are supporting such efforts as well. For instance, the National Institutes of Health now require posting of articles derived from research they fund in the open-access repository; and the Howard Hughes Medical Institute (HHMI) as well as the Wellcome Trust require any scholarly articles on research they fund to be made openly accessible. A bill now going through the US Congress, the Federal Research Public Access Act , would require that US Government agencies with annual extramural research expenditures of over $100 million to make manuscripts of journal articles stemming from research funded by that agency publicly available via the Internet. The manuscripts will be maintained and preserved in a digital archive maintained by that agency or in another suitable repository that permits free public access, interoperability, and long-term preservation, such as the one being developed at Duke. The law would require that each manuscript be freely available to users without charge within six months after it has been published in a peer-reviewed journal.
• A list of the many institutions and funders that already have similar policies can be found here: http://www.eprints.org/openaccess/policysignup/