Based on Bush's margin of victory this year, CO, FL, VA are likely safe for 2008. IA, NM, NV are too smal to count as the big swing state.
I think that Florida's vote was partially affected by the hurricane thing and Bush's reaction, which was handled quite well. If you were to "even out" the country (which I know you can't really do, but still), Bush would have won 50.87-48.32. If it was not for Bush's excellent handling of the hurricane situation, this could have been much closer. I think Florida remains a swing state, but with a tiny Republican tilt.
Colorado was a decent, but not huge win - 5.67 points. Adjusted for national average, this is 3.21. A Republican lean there, easily.
Virginia was, adjusting for national average, 5.74. If the Democrats win this in 2008, they won't need it. Bayh could probably carry it narrowly.
The lack of linear trending of states is an important consideration in Ohio, a state pounded by job losses. Bush smartly made social issues the major vote. If Bayh is the 2008 nominee and the job market is still poor in Ohio, he will carry it fairly easily. If it is good, it will be a true fight, with a Bayh advantage. Other non-midwestern nominees would have a small advantage if there are major job losses, and have an uphill battle if there weren't.
Kerry sucked profoundly in rural PA. A good midwestern populist like Bayh would do well in Pennsylvania, while any other candidate would make it a Democrat-advantage swing state.