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 
http://www.nigelholmes.com/home.htm
Explanation Graphics at its best
http://www.visual-literacy.org/
Expectations regarding the methods and responsibilities of Designers and Researchers are changing. Ethnography has evolved as one of the major skill set for the designers to acquire.
AIGA, in collaboration with Cheskin, has produced a simple and straight-forward primer introducing the crucial role that ethnography plays in designing.
http://www.aiga.org/resources/content/3/7/4/5/documents/ethnography_primer.pdf
