She's dogged by this scandal in Alaska where it seems she is, at best, dodging the truth a bit and, at worst, guilty of using her governmental influence for revenge against her former brother-in-law.

I'm thinking, especially as the investigations are apparently scheduled to finish up prior to Election Day, that this is sort of a head fake. 

Here's the possible scenario:

Today: Palin is chosen as VP - several pundits' heads explode as they try to figure out why McCain would pick someone so inexperienced, essentially throwing away one of his more effective lines of attack against Obama.  Palin's conservative bona fides, gender and personality are scrunitized - press coverage is widespread, overshadowing the DNC's press coverage.

September: Obama's campaign focuses on neutralizing whatever assets she brings to the ticket.  The scandal figures fairly prominently, particularly as more details come to light that throw more doubt on her innocence.

Early-ish October: Some detail emerges that proves her complicity in the scandal (perhaps the e-mails that she is asserting Alaska's version of executive privilege over). 

Mid-October: Palin *resigns* as McCain's VP pick saying she "doesn't want to distract from the campaign".  McCain then, within a day or two, springs his real VP pick (whomever it may be), leaving almost no time for the Obama campaign to pivot and readjust.

Now, this is pretty unlikely, as I suspect it more-than-likely backfire on McCain if it played out like that.  It's interesting to think about, though - and I suppose it *could* happen...