Actually, it's been pretty much a statistical dead heat since March.
McCain still has a tough row to hoe and I can't say I think his campaign so far has been very well-run or focused. His speech after Obama finally rammed the stake through Hillary's heart was pretty abysmal and only served to highlight the fact that he is not going to compete with Obama on speech personality. He's given the Democrats some good ammunition with his (grossly misrepresented) comments about troops in Iraq for 100 years. And he has yet to offer a cohesive, compelling theme for his candidacy, the kind that casual political observers latch onto in the way they do "Hope and Change." Sometimes I wonder if his strategy before the GE is to hang back and let Obama make the kinds of rookie screw-ups he made during the primaries.
The thing is, McCain's almost non-existent campaign and almost non-existent spend (particularly compared to the massive amount of money being spent by the Obama campaign) make it even more remarkable that the race is still, essentially, a tie. There are some goofy outliers, like the Newsweek poll that had Obama up 12 points, but looking at the long-term trends, it's hard not to see that as either an anomaly or as a result of poor methodology.
Add to this the fact that a pretty good portion of the major media are in the bag for Obama and have been pursuing an "Obama is inevitable" story line and you have to admit that maybe Obama is not the juggernaut he has been made out to be. Interestingly, in this campaign season, the last person you want to be is the "inevitable" candidate. Just ask Hillary.