Perhaps someone else made this point already, but one final point regarding the SUSA state-by-state national poll.
In states where both Obama and Clinton have campaigned extensively, Obama does significantly better against McCain.
Feel free to quibble, but my cutoff for "extensive" campaigning is three days or more.
For example, in the early primary states:
Iowa: C down 5, O up 9
Nevada: C down 8, O up 5
New Hampshire: C down 8, O up 2
South Carolina: C down 6, O down 3
This averages out to Obama doing 10 points better in the states where both Obama and Clinton have spent the most time.
In the February states, the only state I remember both candidates campaigning extensively was Wisconsin. Obama does 7 points better there.
Wisconsin: C up 4, O up 11
Then there is Texas and Ohio. Here too, the pattern holds, although Ohio is a wash.
Ohio: C up 10, O up 10
Texas: C down 7, O down 1
Lastly, and perhaps this is a reach, but I think it may be worth including Maryland, DC, and Virginia in this mix. Although neither candidate spent a ton of time campaigning in these states, I don't think it is unreasonable to assume that the voters living in the DC area are exposed to more political news, and hence are more familiar with the candidates. There is no polling from DC itself, but Obama does better than Clinton in both Maryland and Virginia.
Maryland: C up 9, O up 13
Virginia: C down 10, O even
Clearly, its all premature and its just one poll, but for me, this data points towards two possible conclusions. The first is that the more voters get to know Obama, the more they like him. The second is that no one should be concerned about his deficiencies in Pennsylvania and Florida, because he really has not campaigned there yet.
It will be interesting to see where these numbers are after the Pennsylvania primary. Who knows, maybe a long primary is not so bad after all?