The data shows a 3.8% lead for McCain with a margin of error of 2.1%. So a slight lead, statistically. Zogby also provided data for survey questions where the vice presidential candidates were not mentioned. The numbers for this case:
So the race tightens if Palin and Biden aren't in the picture. Note that Obama's numbers are unaffected without Biden; McCain looses about 1 point without Palin.