KEY POINTS:
During the primaries, when Hillary Clinton was talking up her shooting prowess and throwing back shots, Barack Obama mocked her as Annie Oakley.
Now Annie's got her gun, she's entered the contest and it's aimed right at the Democrats.
The question still to be answered is whether the ammo is for real or whether Sarah Palin will be blasting blanks.
So far, John McCain has chalked up a few tactical successes with his pick of the 44-year-old Alaska Governor, mother of five, enthusiastic fisherwoman and gun owner.
He wanted a news splash big enough to cut short contemplation of Obama's nomination speech on Friday and the messages of last week's Democratic convention.
He wanted his party enthused and united heading into tomorrow's Republican convention. Judging by news reports, blog posts and commentaries, the far-right evangelical wing of the party is revelling in having one of their own at the top of the ticket. Many other conservatives welcome the injection of youth, spunk and glam into the grey old party's team.
Although some conservative commentators have pointed out the potential pitfalls, the possibilities of Palin's selection should not be underestimated.
McCain, with this selection, has adopted the Rovian approach of going for his opponent's strengths.
He's trying to wrest the mantle of "change" from Obama, saying the Democrat talks change while he brings change.
Obama leads among female voters but McCain is trying to lure members of Clinton's disaffected flock and some of Obama's young voters.
McCain also hopes that by picking someone with a reputation as a reformist and ethics-buster he creates a ticket of character and reminds voters of why they liked him in the first place. He also hopes the issue of accountability will help him with independents.
Choosing someone with down-home charm and likeability should also be a plus. Remember those "bitter" types "clinging" to their guns and God? Palin can talk their language as much as her opposite, Joe Biden. She describes herself as a "hockey mom" juggling career and work.
But once the novelty dies down, the obvious problems with Palin's selection could surface and dominate discussion. Some of the assumptions McCain has gambled on could collapse like a house of cards.
WOMEN
For many women the selection is likely to smack of tokenism. Hillary supporters wanted her for herself and her policies - does McCain think any woman will do? And would any man with Palin's record have even be considered?
Whereas McCain's moderate policies on climate change and immigration muted his conservatism in the public eye, strapping Palin to McCain makes the choice for female voters stark.
Palin is so anti-abortion she rejects it even in cases of rape and incest.
She supports the teaching of Creationism in schools is against gay marriage and backed the ultra-conservative Pat Buchanan in 2000 ahead of McCain and George W. Bush. She is a global warming sceptic and supports oil drilling in the Arctic National Wildlife Refuge.
INDEPENDENTS
The problem with the Republicans' presentation of Palin as a feisty reformer taking on oil interests and the corrupt, party establishment in Alaska is that she herself has been accused of an abuse of power. Voters could also be reminded of previous incidents of Republican sleaze.
CHANGE VERSUS EXPERIENCE
Palin is a graduate of the University of Idaho who up until two years ago was mayor of a town of less than 9000 people. References on news sites after her selection to George Bush snr's pick of Dan Quayle in some ways miss the mark - Quayle at least had four years in Congress and eight years in the Senate for Indiana before he was chosen.
Republicans have trotted out the fiction that Obama is less experienced than Palin - which at least puts pressure on the Democrats to directly, comprehensively, refute that charge.
Obama is a former president of the Harvard Law Review, community organiser, member of the Illinois state senate, and law lecturer, who has run campaigns for the House of Representatives and the Senate. At the Senate he has been a member of the foreign relations committee and been involved in legislation to control nuclear weapons and boost public accountability in the use of Government funds. He has spent more than a year creating and debating domestic and foreign policy for his campaign.
Palin does have governing experience - unlike McCain, Obama or Biden - but of a state with less than 700,000 people and for less than two years.
Selecting a running mate is considered the first presidential decision a prospective president makes.
The bottom-line criterion is that he or she has to be capable of taking over if the president dies, is incapable of ruling or resigns - something which occurred in recent memory with John F. Kennedy and Richard Nixon.
Apart from the surprise crises that may arise and which no one can predict, the next president will have to deal with domestic economic, health and housing issues; withdrawal from Iraq; the conflict in Afghanistan; terrorism; Pakistan; Iran and its nuclear programme; the problems of climate change and oil dependency; difficulties with Russia and North Korea, among many other testing concerns.
McCain is 72 and has had bouts of skin cancer. He would be the oldest president yet at time of taking office.
He has spurned the claims of people such as former governor Mitt Romney, who has run a big state, a business and the winter Olympics, and Tom Ridge, a former governor and congressman of a significant state who headed a government department.
When Obama was making his choice, he had enough insight to realise he needed a person with foreign policy experience to help to close his security deficit with McCain but also to help him govern. He specifically said he wanted someone he could trust and who would speak his mind. The selection of Biden didn't contradict any of those statements.
McCain, after saying he would pick someone capable of being president, has not done so. His decision says he is focused more on winning than governing and that he feels he can handle all foreign/security matters as president himself - or with other advisers. Not Palin.
Most worryingly, he is recklessly gambling that he would be able to get through a four-year term without problems. With McCain, there's no parachute.
McCain has undercut BOTH his central arguments: That he is ready to lead and Obama isn't; and that he can bring effective change to Washington.
First, if McCain is experienced enough to lead, his deputy should be too. Second, had he tapped a Washington outsider who was also experienced and a credible stand-in president, his argument about bringing real change would have been more authentic.
There were able women he could have chosen, such as his campaign chairwoman, the former head of eBay, Meg Whitman, 52.
But because Palin lacks national and foreign policy experience and doesn't meet any objective measure of a credible president, the selection looks reckless, cosmetic and gimmicky. Would she actually be a real partner in government?
McCain is also risking his previous great advantage - his candidacy's sense of safety and reassurance in comparison with Obama.
And he opens the door to discussion of his age and health as a legitimate campaign topic.
Ultimately the success or failure of McCain's gamble will rest on Palin's shoulders. It's a big ask to expect a political rookie to handle the relentless media spotlight, let alone the vice-presidential debate against Biden.
The Democrats will have to handle criticism of Palin with care and a high-profile role for Clinton will be crucial. It could be that Obama will have to spell out what Clinton could do in an Obama administration.
The Democrats will make hay over what the selection says about McCain's judgment and will hope the public may - remarkably - decide that the Democratic ticket is the safer option.
