1. A method of persisting a node's reputation in a network having transient network communities where a collection of the nodes making up the network may change over time, comprising steps of: using a persistent node identifier for each node in the network, even though a different network address may be assigned to the node upon entering the network multiple times; creating a mapping between the persistent node identifier of each node and a current network address used by that node; and recording results of each node's behavior as it interacts with other nodes in the network, wherein the mapping allows associating the behavior with the node even though its current network address may change.