That is a common misconception on FR. The polls were about right on Bush-Kerry. However, they could be wrong this time. I think McCain and Sarah need to spend more time in VA instead of campaigning in states that are a lot less likely to pay off.
The difference this time around is Kerry had abandoned VA about a month before the election. Obama and the DNC/DCCC are pouring a ton of money into VA, probably through Election Day, so McCain/Palin must respond. Whether this proves to be a smart or foolish use of Dem money remains to be seen. But all these arguments about northern VA turning blue, Virginia turning purple or blue, Democrats starting to win races... they've been around for many elections.