Interesting breakdown from Emory political science professor Alan Abramowitz:
Number of states decided by less than 5 points in 2008: 7, down from 12 in 2000 and 11 in 2004. Percentage of electoral votes in those states down from 26% in 2000 and 25% in 2004 to 17% in 2008.
Number of blowout states (10 percent plus) in 2008: 34 plus DC. That's up from around 25 in 2000 and 2004. Percentage of electoral votes in blowout states up to 71 in 2008 from 57 or 58 in 2000 and 2004.
Average state winning margin in 2008 at around 17 points, up from 14 or 15 in 2000 and 2004.
Conclusion: more, not less polarization in these results. The country is more, not less divided than ever. While there are more blue states, the divide between the red states and blue states is larger than ever. There may be only one United States of America, as Barack says, but the divide between the red states and blue states is deeper than at any time in the past sixty years.
And the correlation between 2004 Bush margin and 2008 McCain margin: .95. So same divisions are four years ago, only deeper.