Similar to the concept of parallel conversations I wrote about earlier this year: inattentive trust building : passive trust building : network connectivity: "There is a theory that a significant part of trust building occurs outside of the time when someone is "attentive" to you.
When you and I are talking and we are interacting that only builds a certain type of relationship or trust. The real depth of trust building comes as I observe how people act not with me but others...Direct online interaction robs the very important inattentive trust building components to relationships. Twitter, facebook, etc. provide a unique window into watching someone without paying direct attention to them."
See also Thomas Vander Wal's post on Sharing and Following/Listening in the Social Web, which discusses the shift from broad line listening and sharing online to more "granular" (think twitter).