A dear colleague, Amanda Williams drew my attention to the Encyclopedia of Interaction. The specific article suffers as it is focused on a Philosophy of Interaction in a commercial design setting. I also think it’s treatment of Heidegger’s concepts of ready-to-hand and present-to-hand are off the mark. Still, it is a good starting point for me to start tackling what interaction is

http://www.interaction-design.org/encyclopedia/philosophy_of_interaction.html