It’s a 4 point lead, with the vast majority of it huge turnout in NYC, LA and Chicago — none of which matter.
I cannot recall EVER seeing 8% undecided in a poll 4 days before election day. Add the number of refuse to respond and you have a formula for the destruction of the polling industry.
Look at post 13. According to that the undecideds 4 days before the election appear to have been around 10 or 11 percent.
It's not unprecedented, at least not for this particular poll.
See the 2004 graph here:
http://spreadsheets.google.com/ccc?key=pLKmTgcVm7Pd_N-_t7U2cVQ
You'll have to click the 2004 link at the bottom to bring up that data/graph.
The thing that you are missing is most pollsters push people to pick a candidate. This pollster does not.