Two recent publications cap lengthy inquiries into the impact of Web 2.0 upon scholarly communication practices, and each merits review by library administrators and planners everywhere.
The Mellon-funded study by the Center for Studies in Higher Education (CSHE) at UC Berkeley, Assessing the Future Landscape of Scholarly Communication: An Exploration of Faculty Values and Needs in Seven Disciplines assesses the views of 160 researchers at some 45 research institutions. Released in late January 2010, the publication can be found here.
In September 2009, Loughborough University published PEER Behavioural Research: Authors and Users vis-à-vis Journals and Repositories. The survey takes a look at the practices of some 3,000 European researchers, and like its American counterpart underscores how the practices and cultures of various discipline impact their respective readiness to leave trusted communications traditions for new schemes.
I recommend a careful reading of both.