WKYW-FM in Philadelphia is reporting major road closures in South Jersey as a result of President Barack Obama's campaign swing in support of Gov. Jon Corzine's re-election.   The Walt Whitman Bridge, and local parts of I-95, I-295, and Route 42 have all been closed as the presidential motorcade makes its way from the Philadelphia airport to the Susquehanna Bank Center in Camden, the station says.  That means New Jerseyans attending today's Giants vs. Eagles game in Philadelphia who did not arrive early are now likely to be very late.  The same bridge and roads will close again an hour later as Obama returns to  the airport for his flight to Newark.