Americans at risk then he is in direct violation of his sworn duty that he takes at his inaugration.
Classified or not. This instance jeopardized Ms Plame and her fellow CIA co-workers and in doing this it in turn puts at risk the lives of American's as the CIA is a tax payers operative that provides protecting the citzenry against all enemies foreign and domestic.
If Ms Plame has her identity busted then her husband and daughter's life go in jeopardy after second one because if 1 and 1 are put together then an enemy agent simply tracks her home.
In the Sworn Oath of office of a President he swears to defend and protect the Constitution of the United States. When he put Ms. Plame identity then he violated the Constitution's binding to guardsafe against foreign and domestic enemies. There were other agents jeopardized with this news and it wouldn't matter if it weren't classified only that if it were unknown to the enemies both foreign and domestic. Doing so removed loyalty in the execution to the protection of the CONSTITUTION!
The President should have not played the cards the way he did. You can't stack the deck and we have been trying to teach Texan's that for years. Well the men anyway.
Compromised our lives for politics. Impeachable for breech of sworn duty. Failing to defend and protect. Crime of the highest nature.