The latest polling trend lines suggest that the presidential race is tightening a little bit. Of course, they pretty much always do in the final weeks. Keep in mind that it's almost unheard of for a major party candidate running in a non-incumbent presidential election to get less than 45% of the vote. McCain, whose numbers are currently in the low-40s, is likely to see some improvement as Republican-leaning independents find their way home. Also, Obama's most recent surge in the polls was largely driven by the financial sector crisis. The crisis still exists, but people are getting used to it as the status quo. You just can't leave your jaw scraping on the ground every day.
But why the sudden turnaround? I was somewhat surprised to see the jump in McCain's numbers right after the third debate, which the public overwhelmingly determined to be an Obama victory. Is it possible that the Joe the Plumber gambit is working (although evidence says otherwise)? Or maybe some conservative independents, even if they thought Obama won the debate, liked the pugnacious McCain, and it made them feel better about the Republican ticket. Or maybe McCain's robo-calls are getting some traction.
It's just frankly hard to know at this point. The most recent round of polls have Obama up slightly and McCain down slightly, on average, since yesterday, but the individual polls are all over the place. And it'll be a day or two before the polls capture the effects of Powell's endorsement (although I'm guessing it'll be pretty modest, if even detectable).
The important thing to keep in mind is that McCain is likely to get at least 45% of the vote. Does he get there by convincing the undecideds to back him, or does he pull it from Obama's share? That strikes me as the key question. Keep your eyes on Obama's numbers. Also, watch the state numbers.