Half Sigma's contention that the GOP is losing the intelligent faction is disconcerting, but the more I look at it, the more inclined I become to put stake in his assertion.
GNXP's Razib has created a convenient comparative table of the white vote by state (including DC) in '04 and '08, showing Kerry's and Obama's respective performances. Obama's gains correlate positively with estimated white IQ by state at .34 (p=.01). In Massachusetts, Obama only garnered 57% of the white vote compared to Kerry's 59%. Our most intelligent state happens to be the one that fielded Kerry, so it's an explainable anomaly. Removing it from the analysis increases the correlation to .39. For each added white IQ point, Obama's performance relative to Kerry's similarly increased one point.
Stepping away from the rate of change for a moment, consider the relationship between the total white vote percentage for the Democratic candidate by state and the state's average white IQ. In '04, the white Kerry vote correlated positively with white IQ at .43 (p=.001). In '08, it has increased to .48 (p=.0004). For every one point increase in white IQ, Obama's support among whites increases a little over four points.
That states with more intelligent whites are more likely to vote Democratic than states with less intelligent whites are is what whiterpeople are after when they insinuate Democrats are smarter and more enlightened than Republicans.
But it does not follow that more intelligent states are more likely to vote Democratic (although smarter states shifted more to the left than duller states did). In fact, the opposite is true*. Bush's total share of the '04 vote and the state's estimated average IQ correlate positively at .31 (p=.03). In '08, McCain's share and state IQ correlate at .26 (p=.07).
In summation, smarter white states give more white support to Democrats than duller white states do. That trend became stronger this election. Smarter states are still more likely to vote Republican than duller states are, but the gap narrowed this time around. Both of these observations lend credence to Half Sigma's assertion that the Republican party is losing its relative ability to appeal to intelligence.
Relatedly, see what Steve Sailer's perspicaciously dubs "The McCain Belt". You might consider ordering Albion's Seed if you've not previously read it.
* At first blush, this may seem contradictory. But keep in mind that nationally the GOP still comfortably wins the white vote while losing the black and Hispanic votes. The dullest white state (West Virginia, white IQ of 97.1) is still more intelligent than the smartest black state (Washington, black IQ of 94.5). Further, even though whites in high IQ states like Wyoming and Idaho are less likely to vote Republican than whites in low IQ states like Alabama and Mississippi are, Wyoming and Idaho are both more reliably Republican than either Alabama or Mississippi because of the large black populations in the latter two states.