The interest towards i-vis has increased over past years, specially in the field of HCI. I recently came across a research paper on i-vis by National Visualization and Analytics Center (USA). Though very scientific in nature this paper looks into how some of the ethnographic and performance techniques can be used evaluate the effectiveness of the i-vis.
http://nvac.pnl.gov/docs/RD_Agenda_NVAC_chapter6.pdf
Good read but requires patience 
