Reading Trust Agents reminded me of the axiom from Bill and Ted's Excellent Adventure, "be excellent to each other."
Trust Agents is less about social media than using social media as a lever (a theme repeated several times in the book) to enhance the trust a specific community (vegans, music critics, mommy bloggers, etc.) has for a particular individual, which correlates to an individuals potential to leverage trust into a business opportunity.
I found it odd that near the beginning of the book, Smith and Brogan caution against attempting to build massive numbers of "friends," "followers" or "connections" then later in the book advise that all non-spam friend/follower/connection requests should be accepted.
That is a nitpick, though in a book that is well paced, provides simple guidance on earning trust and, at the end, addresses potential critics with counter arguments. The latter was my favourite portion of Trust Agents.