"In the last few posts we have discussed ways in which badge systems can be segmented, considered, or categorized within existing social structures. And I have hinted at the sociocultural infrastructure necessary for badges to become useful and effective, social, professional, and personal currencies. This concept of currency stems from the notion of badges as elements of trust networks. They may be trust networks that exist presently but in this post, I suggest that badges may help to engender the creation of dynamic new trust networks."
Via Andreas Link