If you look at the counties where Clinton led, the're mostly urban. Obama led in more counties without major cities. I think this puts to rest the idea that Clinton's win in New Hampshire was the result of hidden racial bias (which would have had to be public in Iowa) because presumably the more rural counties are also more white -- though I guess New Hampshire is pretty much white anyway.
I think the reason Clinton won New Hampshire is easy to understand. She had a good local organization from her husband's background there. He always put New Hampshire and Arkansas at the head of his strongest states politically. With good local organization you can increase turnout, especially in urban areas.
What I think this shows is that Clinton's trained professionalism is beating Obama's exciting and promising amateurism. She did all the things she needed to do to win -- nailed the debates, showed her depth in lengthy discussions with voters, and showed emotion. Obama got caught up with the crowds and allowed his optimism to carry him away.
He also made a huge mistake by allowing Clinton to set the expectations. Think about it -- Clinton went from a double-digit lead to a bare win in two weeks. And she gets credited with being the new Comeback Kid. That's how you compete in the Presidential election, Mr. Obama.