This is the first really hard-hitting ad I've seen from them:
Nicely done. I can't find the article right now, but I read that the Obama campaign is starting to make big negative ad buys but purposefully refusing to buy in DC, New York, and other media centers. In other words, where the McCain campaign has tried to augment their media budget by making reporters aware of their negative ads and getting a lot of free media, the Obama campaign is trying to make the ad buys but avoid the national media and the perception that they're going negative.
