HRC wins. Here are the exit polls, which show the usual suspects in both camps.
Assuming that Obama is the presumptive nominee (for reasons that have been discussed ad nauseum and that credit neither Democratic procedures nor the backbones of the superdelegates), the question is whether and to what degree members of the Clinton coalition will support him in November. Whither, above all, the Catholics, working class and otherwise? Whither white men? (Remember when, as in New Hampshire, Obama received more votes from white men than did Clinton?)
Pennsylvania is something of a microcosm for determing which slivers of the electorate Obama will lose come November. Obama lost Catholic Democrats, and we can expect he'll lose a significant number of them to McCain in the general. Which means that perhaps, just perhaps the GOP will hold Ohio's Electoral College votes.