The Rimm-Kaufman Group published an analysis of a handful of political ads that appeared in search engines (mostly Google). Some of the findings: the blues were more negative than the reds but the reds were more numerous, no ad referenced Bush, only two ads linked to videos. The observation I liked the most: "Blue ads were more likely to include an exclamation point. Red ads were more likely to contain a question mark."
There is something haiku about packing powerful political proclamations into the puny 90 characters of an AdWords blurb. -- thank you, Alan