That's good, I thought I was the only one who didn't.
In the first panel, the woman is apparently agreeing with a silly newspaper article that Dean's message is especially resonating with black voters. The black guy responds by stating the obvious. In the next panel, the reference to black power makes her conjure up an image of him as a Black Panther replete with Che Guevera beret and assault rifle. In the third panel, she returns to her paper, apparently disillusioned by his failure to conform to her preconceived -- and contradictory -- black stereotypes: as a militant 60s throwback, yet fawning supporters of an ultrawhite liberal 60s throwback like Howard Dean. Not fitting either category, she dismisses as unreasonable and he tells her to get lost.
I'm not familiar with the cartoonist's work so I could be totally wrong, but it seems like fairly sophisticated and refreshingly subversive satire for a daily comic strip.