That's interesting, but thankfully they only had 395 tweets so I wonder if you can get something really meaningful with a set of data so small. Looks like there's some correlation with Rommey's voting states though.
A frustrated exclamation of a horribly degrading word to express their anger != A view that African Americans are inferior.
It certainly doesn't show class and I'd bet you'd surely find a higher proportion of racists among those who tweeted that word, but calling them all racists? Wrong.