Armitage was not indicted because the statute prohibiting disclosure of an intelligence agent's identity was not violated. But Fitzgerald plowed ahead with an inquiry that produced obstruction of justice and perjury charges against Libby, though there was no underlying crime.A couple of points from this paragraph - why wasn't the statute violated? Valerie Plame was undercover, wasn't she, although it is still being denied in some areas. And as for the 'no underlying crime' claim, the whole point of the conviction was that Libby lied under oath to prevent the investigation of a crime.
Dan Froomkin, as usual, has an extensive coverage of editorial reaction to the decision.
I have read a lot of comment comparing the perjury conviction to that of Bill Clinton's. What seems to be lost on a lot of right-wing commentators is the question of scale. Lying about a sexual indiscretion doesn't seem quite as serious as lying to cover up the real reasons for going to war.
It reminds me of one of my favourite moments in 'A Hitchhiker's Guide To The Galaxy' where one of the largest forces ever assembled in the galaxy was sent to invade Earth but due to an error of scale was swallowed by a small dog.