Something that is sometimes difficult to grasp from outside the academic world is how strikingly political - and partisan - scientists have become in the last decade. The shift is, I think, something that was brewing for some time, and we can argue the causes endlessly, but the fact is, scientists are liberal and sharply Democratic rather than Republican. It is difficult to think of any identifiable professional, ethnic, or social group that is quite as partisan.
Yes, that's a recent Pew survey that has scientists identifying as D over R by +49 points as oppose to the general public's mere D+12 lean. I personally think the most striking cause was the Bush administrations' "War on Science," a phrase that has gained currency not only with Democratic activists but working scientists frustrated with what they see as one political party's attempt to bury inconvenient scientific facts and obstruct unwanted research.
However, the religious tone of the Republican party from Reagan onward has probably been pushing scientists slowly away from the Republican party for longer. Scientists have in recent generations counted in their number a higher proportion of agnostics and atheists than the general population, and a smaller number of religious fundamentalists.
Another key point to consider is what you consider valuable. Getting a doctorate is generally not an economically sound proposition; the time it takes to finish and get into a tenure-track position has been steadily sliding upward. The increased cost in time and money spent getting the Ph. D. put you behind the curve on pay raises and deeper in debt. Fiscal conservatism has focused intently on the bottom line, lauding the businessman and executive; social conservatism has focused on family life, and the prospect of spending ten years in university is a daunting one if you want to start a family in a timely fashion.
There's another very specific one. Perhaps the largest and most vivid scientific policy question is that of global warming, and for whatever reason, the Republican party managed to align itself wholly in the position of denying what rapidly became established scientific fact.
And perhaps the D+49 (55 to 6) percent party ID gap in scientists has just a little to do with the fact that Obama himself can be described as an academic, but I think the persistent anti-intellectual rhetoric of the Republican party throughout the Bush administration had more to do with it.