There has been a fairly large, and growing, disparity between the numbers obtained by pollsters who are calling cell-phone-only voters and the numbers obtained by pollsters who aren't. According to pollster.com, in the latter polls Barack Obama is leading John McCain by 5.5 percent; in the former, theoretically more accurate ones, that lead is 9.2 percent. Brian Schaffner makes a point I hadn't seen elsewhere, specifically that very few state polls contact cell-only voters. Will this make a significant difference? We'll find out tomorrow. But Schaffner unpacks what it could mean.