Communication (and Coordination?) in a Modern, Complex Organization / Harvard Business School Working Papers, 2008
PDF - http://www.hbs.edu/research/pdf/09-004.pdf
"This is a descriptive study of the structure of communications in a modern organization. We analyze a dataset with millions of electronic mail messages, calendar meetings and teleconferences for many thousands of employees of a single, multidivisional firm during a three-month period in calendar 2006."