I wasn't communicating well, what I'm on about is that knowledge flow in large organisations is not always (or even often) through 'official' channels. I'm thinking of Etienne Wenger's work on situated learning, especially the insurance office example in Lave and Wenger's book.

It struck me that datasets from email, and from sharepoint like systems might help people identify the 'betweeners' in their organisation.

Yes, people do this - it is called Social Network Analysis and has been around a few decades. It is well introduced in http://www.amazon.com/gp/aw/d/1449306462 . There is actually a thorough example of analyzing an organization's "social leaders" and arranging departments to take advantage of them.