From Cornell University Library’s letter to its Congressional representative, in support of the NIH Public Access Policy:
From the perspective of the Library, the Policy addresses one of our major concerns: the long-term preservation of research results published in electronic form. A decade’s worth of research by Cornell Library staff has demonstrated the fragility of most electronic publishing schemes and the difficulty faced by libraries in meeting their traditional role as preservation repositories for published literature. Deposit in PubMed Central ensures that the research results will be preserved in a state-of-the-art digital repository.
The letter is available from: http://www.library.cornell.edu/scholarlycomm/Hinchey%20Letter.pdf.