This oft-asked question needs to be broken down a bit. Matter to the pundits? Of course. They need daily fodder for their articles, and so we're being inundated with Cheney and Edwards stories, pro and con. Matter to the voters? Maybe not, most years. But it's possible that in the cases of Mondale/Ferraro and Gore/Lieberman, where a woman and a Jew were the candidates, maybe.
This year, it's possible that Edwards could help Kerry because he's so different, in every dimension, from Cheney. He's young, vital, populist, attractive, persuasive and so on, while Cheney's the opposite, bigtime. Indeed, during the week Edwards was chosen the rumors of a move to drop Cheney from the Republican ticket have resurfaced.