Kyle Rimkus et al. have published "Digital Preservation File Format Policies of ARL Member Libraries: An Analysis" in D-Lib Magazine.
Here's an excerpt:
In the interest of gaining a broad view of contemporary digital preservation practice in North American research libraries, this paper presents the findings of a study of file format policies at Association of Research Libraries (ARL) member institutions. It is intended to present the digital preservation community with an assessment of the level of trust currently placed in common file formats in digital library collections and institutional repositories. Beginning with a summary of file format research to date, the authors describe the research methodology they used to collect and analyze data from the file format policies of ARL Library repositories and digital library services. The paper concludes with a presentation and analysis of findings that explore levels of confidence placed in image, text, audio, video, tabular data, software application, presentation, geospatial, and computer program file formats. The data show that file format policies have evolved little beyond the document and image digitization standards of traditional library reformatting programs, and that current approaches to file format policymaking must evolve to meet the challenges of research libraries' expanding digital repository services.