The a2k wingnut contingent is a small group which is representative of something much larger...essentially, it is the talk radio/Fox audience (and now represented broadly across the web as well). They ARE plugged into the same amplifier. For the last couple of years, I've been listening to a lot of right wing radio, watching Fox (my wife runs out screaming), and following their activities online. It is a self-validating and self-sustaining echo chamber - which is why they all use the same terminology, voice the same opinions, and hold the same unexamined assumptions. Without this propaganda mechanism, the party would certainly look now much more like it did two or three decades ago.
There's just no question, I think, that the party generally has been dragged right due in great part to the above. Rove and Norquist and Scaife and others could not have done what they've done without this. And even if they personally aren't fundamentalists or anti-choice or whatever, promotion of that 'populist' or nutcase base has served their purposes well. But in the process, they've created a beast that is no longer entirely under their control.
I kind of like Smirconish too. He represents that older type of Republican/conservative who doesn't think education or reflection are prime indicators of lousy, weak-kneed and dangerous citizenship. Clearly, you're right to point to the Palin pick as a fundamental reason so many thoughtful Republicans are supporting Obama. But Palin isn't dangerous only because she is incurious, intellectually narrow and insular but also because she is representative of that wingnut beast that's been created.