is spot on as usual:

It really is the height of strangeness to witness the shrieking and self-righteous rage over the MoveOn ad as though such insinuations are prohibited in American political debates, the Line that Cannot be Crossed. That line is crossed routinely, and has been for decades, including when directed at a whole array of American combat veterans. Ask George McGovern about that. The only difference this time — the sole difference that has so upset Joe Klein and his fellow media mavens — is that it is being directed at the side that typically wields such accusatory rhetoric, rather than by them.