Mike's recommended list of  Must-Reads:

Cassell, J. "Nudge Nudge Wink Wink: Elements of Face-to-Face Conversation
for Embodied Conversational Agents", in Cassell, J. et al. (eds.),
Embodied Conversational Agents. MIT Press, Cambridge, MA, 1999.

Heeman et al.  "Identifying Discourse Markers Dialog"  AAAI Spring
Symposium on Applying Machine Learning and Discourse Processing, Stanford, March 1998.

Cahn, J. "A Computational Memory and Processing Model for Prosody."  PhD
Dissertation, MIT Media Lab. October 1998.

Goffman, Erving. (1983). Forms of Talk. University of Pennsylvania Publication.

 Grice, Paul. (1989). Studies in the Way of Words. Harvard University Press.