Murray's numbers likely moved because of something Murray did, not because of the national mood. The numbers here are what they are probably because this race has not been localized—it's low enough attention that you're just getting a default set of nationalized numbers. And that's dangerous for Smith.
Well, if Murray was able to move her numbers not only against where she was but also against a countervailing shift in the state or national mood over the time, effectively doubling her movement, then Democrats who have money in the bank may have higher hopes than previously thought.
IMHO, this has always been the case, though it was oft overlooked because of all the surrounding pessimism. Boxer will spend her way to victory, too. Feingold is in trouble, because his principles preclude him from doing so.