So I heard this talk at the Cornell Microsoft International Symposium on Self-Organizing Online Communities. The presentation was called "Implications for Future Research; Theory and Methods in Large Scale Analysis of Online Communities." And the three Yahoo presenters were Ravi Kumar, Andrew Tomkins, and Cameron Marlow. Not sure which one those three specifically, but I'm sure you could ask any of them.

I've developed this hobby of sneaking into academic conferences. It works best if when everyone else is wearing a suit and tie, you show up in shorts and a t-shirt. That way everyone just assumes that you're friends with one of the speakers, or else that you're Sergei Brin. :-)