Greg Laden has a nice synopsis of a Science article which discusses the positions of the main US Presidential candidates on science and scientific issues. Basically the three leading Democrats get lukewarm praise, but the Republicans are generally pretty bad, or silent on the issue. The notable exception is McCain, who is interested in energy and climate change.
Of course, when it comes down to it, science just isn’t an issue. Stem cell research is a notable exception, but the debate has largely been about religion. Huckabee and Ron Paul are evolution denialists, but I rather doubt that either of them know much about evolution. And alternative energy? That’s just a way to funnel subsidies to corn states, right?