Andrew Gelman, whose book you should really read, explains how the election was won:
3. The gap between young and old has increased–a lot:
But there was no massive turnout among young voters. According to the exit polls, 18% of the voters this time were under 30, as compared to 17% of voters in 2004. (By comparison, 22% of voting-age Americans are under 30.)
4. By ethnicity: Barack Obama won 96% of African Americans, 68% of Latinos, 64% of Asians, and 44% of whites. In 2004, Kerry won 89% of African Americans, 55% of Latinos, 56% of Asians, and 41% of whites. So Obama gained the most among ethnic minorities.
5. The red/blue map was not redrawn; it was more of a national partisan swing. See this state-by-state scatterplot of Obama vote in 2008 vs. Kerry vote in 2004: