This is obviously a very gutsy pick. An unknown woman who has been the governor of a solidly Red state for less than two years. It could be brilliant, or exceedingly not brilliant, or it could not matter at all.
You can't help but contrast this pick with Biden. Biden was a great choice, but a very conventional one. Palin is anything but conventional. One of the reasons that I liked Biden is that he was chosen not for any specific demographic group but because he is so well-suited to the job. Don't get me wrong: I know Obama's choice is every bit as politically motivated. McCain's choosing Palin, on the other hand, is obviously an attempt to woo disgruntled HRC voters. I applaud his choosing a woman, but it seems very transparent. Are HRC voters just going to vote for McCain because he chose a woman as Veep?
I find it unlikely, but time will tell.
Also, Palin has been governor for less than two years and has never worked in a foreign policy job. Ever. Maybe I'm giving the voting public too much credit, but doesn't this undermine the argument that Obama isn't ready to be President? Basically, McCain is saying this is the person who will take over if anything happens to me. It seems strongly implied that he believes she is ready to do the job. But how can it be that she is ready and Obama isn't? It can't. Which means that McCain's argument about experience is just politics.
One thing that I haven't yet heard anyone point out: Palin is a social conservative who is not associated with the Bush administration. In other words, she pleases the base without alienating the Bush-weary independents. From this perspective it's a good choice.