A Little Background
For those who have never done any research on espionage and intelligence agencies, like the press corps, this is they way a standard covert operation is run:
You need a front, usually an international business. Business is useful, because most international businesses function in a remarkably similar fashion to covert operations - they bribe people, seek information, hide funding sources, use postal boxes and rented offices to avoid taxes and get business.
The front needs a "legitimate" contact, someone who can be researched and identified. Someone with minor celebrity, such as being the wife of an ambassador, is just about perfect. Someone like that could be checked by intelligence services and ignored.
These front operations need to actually function like the businesses they claim to be, so they will actually pursue business and fulfill contracts to prove they are real. Some percentage of the employees don't know they are working for a covert front, and are totally separate from the espionage function.
If the cover on the front is blown, say someone tells the world that the ambassador's wife is actually an employee for the CIA , there is a problem for everyone associated with the front, not just those who were part of the espionage operation. Counterintelligence people don't like being fooled, so everyone will be hauled in and considered guilty. There is rarely any effort to allow those people to prove their innocence.
The Plame case isn't about just one woman, it is about everyone who worked for her covert operation. Dozens of people have been put in danger because of this revelation, not simply one upper-middle-class Washington suburbanite. Most of those in trouble were not involved in espionage; they are simply "collateral damage" in a nasty little personal feud.
For all those people with their talking points: it doesn't make much difference to the innocent people affected whether Karl Rove intended to harm them, or knowingly harmed them, or simply, recklessly harmed them, they are suffering, and some may have been executed. This is why it is supposed to be difficult to get a security clearance: leaks get people killed.