Steve Pinker understates the case when he says that there's a master's thesis in "nucular" studies: I envision dissertations, conferences, endowed chairs, journals, broken marriages…
Actually, I want to comment about just one argument Steve makes, this in passing, about George W. Bush's speech. Steve says that "People generally end up with the accents of their late childhood and early adolescent peers." There's clearly an important sense in which this is true: it depends on what the meaning of "accent" is. Certainly some basic phonological pattern is fixed by late adolescence, along with lexical classes — my upbringing in the New York suburbs left me with different vowels in dog and frog, long and gong, and in the initial syllables of hamburger and hamlet, for example, and that's going to persist in whatever particular phonetic realization I give those words. But my range of variation has broadened a lot since then — I get more general American (or general East Coast) on some occasions, and more sidewalks-of-New-York on others. And I don't think it makes sense to think of these variations as add-ons, corrections, affectations, or in any way less "authentic" than what I grew up speaking. It all feels like me by now.
In this connection, I don't think it's likely that W grew up speaking as he does. For one thing, his Texas accent is a lot more prominent that of his brother Jeb, even though Jeb also grew up in Midland and Houston and moreover stayed in Texas to do his college and law school while W went to Yale and Harvard Business School. They may have the same basic Texas phonology — the raising of front vowels before nasals, the backing of /a/ before /r/, for example — but W "drops his g's" more often, takes monophthongization of /ay/ much further, and generally conveys a more down-home impression:
And while it's of course possible that Jeb is the one who has corrected or adapted his speech, I think it's more likely that W adapted his to the west Texas norm, particularly after he was defeated for Congress in 1978 by an opponent who depicted him as an Easterner out-of-touch with local values. But I don't think W's accent is "fake" — that's part of who he is now, and I imagine it's how he'd sound if you woke him up in the middle of the night.
My guess — and of course I have no direct evidence for this — is that W's adoption of "nucular" also came around this time. The fact is that his dad doesn't say it that way, and it's a word that would have been a lot more common around the G. H. W. Bush place than in the average American household. (You wonder how his parents would have reacted if W had ventured the "nucular" pronunciation around the family dinner table.) And it doesn't seem plausible that W would have adopted the "nucular" pronunciation from his adolescent peers in Midland — I mean, how often are they going to be using that word in the first place? But on reflection, maybe "faux bubba" was unfair. At least, if you woke him up in the middle of the night he'd probably he'd say "nucular," too.
(One reason why this business of "authenticity" is important is that I think you can make a similar point about Obama's "blackcent," as some people have called it, criticizing him for adopting a form of speech the circumstances of his upbringing don't entitle him to. I don't know how much of that he might already have had in Hawaii — certainly g-dropping wouldn't have been an alien feature, even to students at Punahou — but even if he acquired it all in Chicago, that doesn't make it fake or inauthentic. Why should our linguistic self-fashioning have to stop in adolescence while the rest of it can persist over a lifetime? And why should "inauthenticity" be held against you only when you're shifting away from the standard? But maybe this point deserves a more ample discussion than a parenthetical allows…)
A couple of other small points. Re Steve's observations about the pronunciations he heard at the Naval War College: As I think I mentioned, the "nucular" pronunciation is also common among military and defense people who almost certainly know it's considered incorrect. My sense is that for at least some of these people, this is a sort of anti-affectation — by which I mean that if you ask them about it, they'll say they damn well know how the word is supposed to be pronounced. I have an old college friend, an upper-middle-class New Jerseyite with an MIT PhD who works for the DOE, who makes a point of saying "nucular." When I asked him if he referred to "nucular families," as well, he said, "No, I only use 'nucular' when I'm referring to nukes." And in this connection, I wonder if nuke mightn't in fact have influenced the pronunciation of at least some of these speakers, even if it couldn't be responsible for, say, the way Eisenhower said the word.
Carter actually says something like "nukeeuh," which is probably more loss of the "l" in his Georgia speech than a variant of "nucular."
Oh, and Richard Lowenberg has posted a list of well-known people who "should know better" who have been heard to say "nucular."