The Nation gets it right:

The endorsement by the Times, which has backed Lieberman in most of his past races, and which is far more cautious politically than its conservative critics would have America believe, came as something of a shock to Lamont backers. Just a few weeks ago, when I interviewed a Lamont aide in Connecticut, he told me that the candidate was merely hoping for a few kind words from the paper in what was expected to be a pro-Liebermman editorial.

Instead, the Times hit Lieberman where it hurts, ridiculing the senator's suggestion that his support of President Bush's misguided foreign policies makes him some kind of statesman.

No, newspaper endorsements usually don't matter. But this is one that does, because of the devastating content, the timing and placement (Sunday editorial page) and, especially, the standing of the institution that delivered it in the eyes of many of the supporters of the person it was delivered against.

While few voters will probably be swung by any editorial, the voters who do care about what the New York Times says are many of the same ones who cared about what Bill Clinton had to say in Waterbury one (very long) week ago. And Lieberman has made his entire campaign about Clinton in the past week - rhetoric, ads, robo-calls, and non-union-made paraphernalia. So this really does hit Joe where it hurts.