Protecting Reporters Sources

In general I believe that sources should be protected, but only in cases of the public being served and not in cases where reporters are complicitous in doing harm; abettors of vindictive actions such as is apparently the case of Valerie Plame.
Protecting sources in cases of whistle-blowing is different; when the public is served and not being dis-served. The people are participants in government, voting and engaging in the political process, and must be informed, which reporters and journalists help to do.
However, reporters have the "privilege" of protecting their sources, not an absolute right to do so; like some cases of freedom of speech being abridged because of the possibility of harm--such as crying "fire" in a theatre.
Sources should be protected if whatever being revealed needs to be known by the public, to the publics benefit. Too often information is "classified" for purposes of covering up government bad deeds, detrimental in some manner to the public good, rather than for "national security" reasons.