I've been underwhelmed by some of Obama's ads, particularly his efforts to define McCain. But he really lands some blows with this one: 

Social Security privatization is the loose string that unravels McCain's whole sweater. Not only does it closely tie his economic agenda to Bush's, it connects the financial market crisis to people's personal bottom line in a way that's downright alarming. It's pretty easy to appreciate how disastrous privatization would have been after a week of stock market freefall.

--Noam Scheiber