Gaffe or gotcha, I think this issue is going to make barely any difference. It's something people point out for a potential nick in the jar and that's it. She could have just misspoke, or she could have been clueless.
Either way, the subject of what Palin said is just over most people's heads and/or has a 'boring' theme, even if it should really be an important noted gaffe/telling of a major weakness rather than a gotcha. These things also don't merit much media attention because it isn't sizzly stuff. They like whipping up controversy to get sales and egghead issues don't do that.
These are the kinds of messages that more people 'get' that are coming out insofar as hits on McCain and Palin, which I expect will pile up as the race continues such as your standard "I call you out on your BS" kind of ad:
YouTube - "No Maverick" Ad
or a humorous characterisation incorporating a weakness admitted by an opponent:
YouTube - McCain Don't Know Much...
or unofficial gags like:
Michael Palin for President
and likewise stuff on John Stewart on the Daily Show, etc.
This is the kind of stuff that works the massive 'man on the street' moreso than these kinds of issues.
McCain, Palin, Obama and Biden can wonk on each other but it's the kind of stuff like the examples I cited that will stick with more people (and even with the groups I mentioned because they're easier to remember), never mind all the spins, gotchas, mischaracterisations, attacks, and other slick stuff they and/or their supporters all pull that really don't add up to dogshit on true merit but succeed in winning over voters. As Mencken wisely put it: "No one ever went broke underestimating the intelligence of the American public." They have to keep it simple and dumb it down on alleged facts, outhustle on the hustle insofar as spin, and let all the knuckledraggers out there outsmear the smear (he's a Muslim, her kid is her daughters' etc...y'all know the drill on that).