This is a tough issue.
Reporters have certain rights in covering stories.
They also have an obligation to report the greatest good for the greatest number of people. As hard as it may be, they do have certain rights to report the truth to the public, even if that means breaking a promise to a source. Journalists must realize that these people are not schooled in the legalities of what they say. The very fact that these sources came out with their stories should be enough to establish trust with them. For example, when a woman promises to give the media information about her AID's stricken child in exchange in anonymity, they should stand by their promise.