No question he is going to be the nominee. That has not changed at all. He will still win North Carolina by at least 10 points and I believe he will win Indiana, but even if he loses, he won't lose by more than 5 points.
The last couple of days have been wasted with the distraction of his former pastor, Jeremiah Wright. The sad part about it was that Obama gave a masterful speech on race in Philly. He did not abandon his pastor, but tried to explain the context of race in America. This allowed Wright to rebuild his image and quietly slip out of sight. However, for some reason, Wright's ego is too big to avoid the limelight. His comments two days ago were ridiculous and Obama rightly denounced him. That should be the end of the story, but it will go on for another day or two.
If I were Obama, I'd get off the Wright story by simply getting back on message about the economy and Iraq. The media is going to push the story, but just like the ridiculous focus on the whether or not Obama wears a 10 cent flag pin, most Americans won't care in the end if they feel that he can bring about change. That is what made him popular to begin with and that is what he needs to get back to.
The bottom line is this - Hillary and McCain represent the Washington elite establishment. They have been in Washington forever and have not been able to bring about change. Obama needs to play up his populist message and his role as an outsider. If he does that, he will be fine in the general election (again, he is going to be the Democratic nominee).