Vice Presidential candidates are important, I'm told, three times only. The day they're chosen, at the convention, and at the VP debate. Well, Sarah did fine at the first, even better at the second, and my impression (I didn't watch) is that she did quite well at the third.
And that's the end of that. It's pretty clear her boss is going to come in second, which means that on a Wednesday in early November she'll be going back to Wassila, a place none of us had ever heard of until 5 weeks ago. I expect, however, that once there she'll take out a subscription to the NYT, the Economist, and a few other important news outlets. She then has about two and a half years to work on her main weakness this time, namely that she knows nothing about the world and not too much about the USA. She seems intelligent, so 30 months will easily be enough to fix that. Expect her to be back with a vengeance next time round, perhaps even taking on President Obama himself.
In which case, John McCain's most important legacy at the presidential level will have been to invent Sarah Palin. Whether this will be good or not, I have not the faintest idea.