That's what it would be if Palin were indeed nominated.
First: McCain is making a play for Hillary supporters. He's putting a woman on the ticket because Obama didn't; he's hoping that these women's loyalty to their gender is greater than to Hillary herself. Considering the politics of the run, that's not a bad assumption.
But there's another aspect. Everybody's been concerned with his age, right? The logical implication of that is that his VP might end up president if something happens to him. At the very least, it's very possible he'd only run for one term. Then you have a woman VP ready to run for the nomination of the Republican party; and she'd likely win that nomination, thus neatly cutting off Hillary's main case for support in 2012. I doubt Clinton would even get nominated.
And since everybody knows all this, what McCain's really doing is saying "vote for me, women and you have a pretty good shot at a woman president within the next five years." It's not even that objectionable a tactic; the Dems can't easily rip him up for it, or face blistering questions about why setting things up for a woman's presidency is a bad thing, exactly.
She's a dark horse, and I doubt she's been as vetted as thoroughly as she could. She may have skeletons, and it's even possible she's tied to Ted's shenanegans. And there are going to be men in the Republican party who are not happy voting for a woman. But I think this "vote for McCain, possibly get a woman in the Oval Office" trick is what he'd be going for.
Edit: Her big problem with women is going to be her anti-abortion stance. It will limit her appeal to feminists, I'm sure, but disconnected independent women who don't care about anything but a woman in the White House might well overlook it. Her environmentalism might also alienate the economic conservatives a bit, but if she really is anti-abortion, that'll probably make up for it.
Edit 2: Ok, according to Kos, she's also a big creationist. And she's only been in office since 2006? I really do wonder what's in her past.