danah boyd has posted the text of her ETCON talk, Revenge of the User: Lessons from Creator/User Battles.
Asking favors is fundamentally different than offering them. People gain by being bridges. Thus, to be able to tell you about a job gives me whuffie in our relationship. Feeling pressured to connect you to an open job makes me uncomfortable. In all of the networks described above, the bridge got to control the information flow. In Milgram's "Small Worlds," if you didn't know that i knew the target person, you may not have tried to pass it on to me. If you don't know that i am dating someone who has something that you want, you won't try to pressure me into giving you access to it. Thus, i can choose when to reveal my connections in a situation where i can come across as being helpful, rather than being put in a position to feel cornered. Revealing the network shifts the power.