The 538 blog (probably the best election site this year) has been devoting quite a bit of attention to the disparity in voter contact between the Obama and McCain campaigns.
The current disparity is huge, but I would be wary of putting too much emphasis on such statistics relative to polls. In the lead up the 2006 election, Karl Rove kept predicting, in the face of just about every poll, that the Republicans were going to keep their House and Senate majorities. At the time, most people assumed that Rove was just blowing smoke in an effort to keep up confidence on the GOP side. It turns out, however, that Rove really did believe that the Republicans were in good shape since he was looking at data on GOP voter contact and believed that it was more reliable than the polls:
The polls and pundits pointed to a Democratic sweep, but Rove dismissed them all . . .He wasn’t just trying to psych out the media and the opposition. He believed his “metrics” were far superior to plain old polls. Two weeks before the elections, Rove showed NEWSWEEK his magic numbers: a series of graphs and bar charts that tallied early voting and voter outreach. Both were running far higher than in 2004. In fact, Rove thought the polls were obsolete because they relied on home telephones in an age of do-not-call lists and cell phones. Based on his models, he forecast a loss of 12 to 14 seats in the House—enough to hang on to the majority. Rove placed so much faith in his figures that, after the elections, he planned to convene a panel of Republican political scientists—to study just how wrong the polls were.
Voter contact is an important way to target voters and can account for a few points on election day, but I’m skeptical that even the best field operation can carry a state when the polls are running strongly against you.