Prof. Stan J. Liebowitz has written on File Sharing: Creative Destruction or Just Plain Destruction? Conclusion: "Data limitations not withstanding, the evidence seems compelling that file-sharing is responsible for the recent large decline in CD sales for which it has been blamed."

He also has available a draft of a forthcoming review of William Fisher's Promises to Keep: Technology, Law, and the Future of Entertainment. to be published in Issues in Science & Technology.

Both are products of Prof. Liebowitz' new Center for the Analysis of Property Rights and Innovation, which says of itself:

Academic research is our number one product. To that end, the main focus of the Center will be to engage in academic research analyzing the role of property rights, comparing alternative forms of reward systems, and examining business models and propositions under different property rights rules.

See here for current research being supported by CAPRI, here for a list of working papers.