I still have the Washington Senate race as one of the four closest, despite Republican Dino Rossi taking a decent lead over Democrat Patty Murray in recent polling. This is why: both candidates have been capable of rattling off good polls, and one new result at any time can come out in favor of either candidate.
Rossi had run off three polls in a row if we discount the Elway Poll which has been grotesquely biased toward Patty Murray all year long. Before that Murray had four, again ignoring Elway. I mean seriously, how bad is Elway? At one point it showed Murray +17 when the polls around it showed Rossi +10, Murray +2, and Murray +4.
So some back and forth is to be expected, much as we've seen in the Nevada race, the Illinois race, and as we're starting to see in the West Virginia race. CNN/Time's new result of Murray 51-Rossi 43 (MoE 3.5) is huge for her, without a doubt, but so was that poll a little while back with Rossi up 6.
That 88% victory chance for Murray will certainly weigh in my next projection, no doubt about it. But unless it's followed up with a string of similar polls, and not a continued mix of Rossi leads with Murray leads, it in itself is not predictive of a new shift in the race. It takes a trend to do that.