In order to support NIH-funded researchers at the University of California, William T. Tucker, the Executive Director of the UC Office of Research Administration and Technology Transfer has written a Letter to Publishers (PDF).
When submitting an article to a journal for possible publication, UC authors should attach a copy of this letter along with their manuscript. This letter ensures University of California support for author compliance with the NIH mandate.
For more informatiion see:
Effective April 7, 2008 anyone who publishes an article based upon research funded by the National Institutes of Health (NIH) will be required to submit an electronic version of their final, peer-reviewed manuscript to PubMed Central. This groundbreaking policy gives the public full access to taxpayer-funded research within 12 months of its publication.
How to comply? If you have received NIH funding and have had an article published in a peer-reviewed journal, you will need to comply with this policy. The NIH states that the submission process usually takes less than 10 minutes. See the NIH Public Access Policy page for more information on how to comply.
There are a number of journals that submit articles directly to PubMed Central on behalf of their authors. When you publish in one of these journals, no further action is required on your part to comply. See the complete list of Journals That Submit Articles to PubMed Central (compiled by the NIH).
For more background on this topic refer to Hot Topics: NIH Mandate