Smart post on what Rove has wrought, at the blog huffingtonpost.com :

Dirty Plot Or Accidental Genius?

If Karl Rove planned this — which I doubt — he really is a genius:
1.) He leaks to Time’s Matt Cooper in such a way that he avoids the law’s intent requirement for criminal liability (today’s Newsweek notes that Cooper’s email shows nothing indicating Rove knew or revealed that Valerie Plame was an undercover agent, only that she worked at the CIA).
2.) The ensuing grand jury investigation dramatically weakens the news media and future leakers, as reporters must decide whether to testify or go to jail, and even turns Rove’s foes in the public against the reporters involved because they are seen as protecting him.

ELI SANDERS adds: For example of such foes, see FEIT, JOSH.

In other words, by making himself a protected source who loses that protection, Rove makes it easier for the government to use federal courts to target all leakers. This would give Machiavelli a migraine.