This started as a comment in response to Mouschi's Thoughts of a Southern Liberal.
Dean's comments were the (too interesting/incendiary/antagonizing) rhetorical flourish on an important message: we are seeing the completion of the political shift from Democrats to Republicans in the South.
The issue has interesting parallels with Dean's own relationship to sexuality politics and with the Cuban embargo.
It's Lincoln's fault
From the Civil War to the 1960s, Democrats won (in no small part) because Lincoln was a Republican. Many southern Democrats were much more politically conservative than their northern counterparts, but would never vote Republican because of that party's role in the Civil War.
In the 1960s the national Democratic Party repudiated racist politics and identified itself with desegregation and voting rights. This began the slow dissolution of the segregationist southern Democratic bloc, as Democrats--voters and elected officials--switched parties.
During this process the Republican Party incorporated the racial politics of the old Democratic Party, from supporting states' rights when the issue is federally mandated nondiscrimination to celebrating Confederate history to simply being racist.
Hey, the North won...
Race plays a big role in many people's political decisionmaking, whether it's the rural South or the urban North. But the North won the Civil War so there was a limited base of segregationist Democrats in the North--the transition to anti-discrimination and desegregation happened quickly among Northern Democratic voters and officials. (The repercussions of FDR being the "big-government liberal" Democrat have been greater than those of Lincoln being Republican in Northern politics.)
Dean is positing racial politics as a large reason that working-class Southern whites vote against their interests when they vote Republican.
And he's right.
It's the metonomy, stupid
Now that Dean has made the necessary apologies--and I don't mean that flippantly--we can recognize that Dean was using metonymy, not implying all or a majority of working-class Southern whites drive pickup trucks with Confederate flags, we can see that it;s a strong rhetorical device.
People who put the Confederate flag (or any flag) on their car don't make their car run better, but they make themselves feel better.
Working-class Southern whites who vote Republican are doing about as much good for themselves as putting the Confederate flag on a pickup does for the truck.
How are poor Republican whites like Cuba?
I really think Dean made a crucial step forward in the debate on Tuesday when he stated that when he signed the civil unions bill he was uncomfortable with homosexuality personally, but he distinguished his feelings from what he thought was right under his political beliefs. Because of that political act, in the following years he actually interacted with gay people and his personal feelings have changed.
Much as Wes Clark said that the only way to bring change to Cuba is to embrace it economically and let capitalism do its work, even though we repudiate Castro's politics, the only way to bring change to racist (or "uncomfortable with blacks") working-class Southern whites is to embrace them politically and let the Democratic platform do its work, even though we repudiate racism.