There are some exceptions to this rule. One is if the individuals are describing something that is in their field of expertise. This letter specifically addresses the scientific issues that have been hurt by the Bush administration and which look to be better understood and appreciated under an Obama administration. In this sense, the fallacy is still true, we shouldn't just accept their conclusions because of their authority, but since it is their field of expertise we can give their opinion more weight than we would if it wasn't their field of expertise. In this case, the weight of their authority and the weight of the evidence of their position leads to accepting their position.
Now it is important to understand that their endorsement is really only about science and technology with a passing nod to the notion that these are the tools we must use to fix the other mounting problems we face. So, if the economy and national defense are more important to you, then you would have to decide if science and tech are more important than other factors such as diplomacy, military strategy, and invisible hands then you might agree with these Nobel Laureates. But their being Nobel Laureates isn't sufficient by itself to make the conclusion true.
The Rational Moderate