Here are some articles on folksonomy that I found in a reading list on the Indiana University School of Library and Information Science website.

Peterson, E. (2006). Beneath the metadata: some philosophical problems with folksonomy. D-Lib Magazine, 12(11).

Vander Wal, T. (2007). Folksonomy coinage and definition.

Quintarelli, E. (2005). Folksonomies: power to the people

Mathes, A. (2004). Folksonomies: cooperative classification and communication through shared metadata.

Golder, S. A. & Huberman, B. A. (2006). Usage patterns of collaborative tagging systems. Journal of Information Science, 32(2). 198-208.