Just a few hours later, on his birthday and her 20th wedding anniversary, John McCain made it official: Sarah Palin now takes the last spot left on the major party presidential tickets.

Palin is guaranteed to please a Republican base that has just finished writing a conservative platform, and which has a good deal of trepidation about McCain's reliability as a conservative. She is pro-life (in fact, a member of Feminists For Life), a proponent of traditional marriage, a lifelong member of the National Rifle Association (and hunts moose.) She has five children, the youngest of which has Down Syndrome. Her insistence on having her son, Trig, regardless of the medical pressures, has made her a heroine to the pro-life movement.

As governor, she has an 80% approval rating, and she is known for her frugality and willingness to cross her own party in pursuit of principle, most notably when she resigned as Ethics Commissioner of the Alaska Oil and Gas Conservation Commission, not only objecting to the panel's lack of ethics, but turning in both the Republican state chairman and the former Attorney General, who resigned.

While only time will tell how good this choice might have been, on this, the day after the Democrats' momentary triumph in Denver, she is an astonishing pick--and a McCain move that has sucked all the air out of the Democrats for the long holiday weekend, which leads directly into the Republican National Convention.

(It should be noted that it is possible that the convention may be postponed or disrupted in some fashion, due to the oncoming hurricane in New Orleans, which would call the attention of many of the principals back to the Gulf Coast. Interestingly, such a postponement would not be bad for McCain, since the minute he takes the nomination, he is limited in his campaign spending to the $85 million and change public financing will provide, while Obama is unlimited in his expenditure of funds, having rejected public financing.)

Palin becomes the only one of the four major figures on the two party tickets that has any executive experience at all. Though she has no foreign policy experience (despite its distance from DC, Alaska is not a foreign country), she does have something in common with the foreign-policy-heavy Joe Biden. Biden's son, Beau, is set for deployment to Iraq in October; her son, Track, is being deployed to Iraq next month. (John McCain's son, Jimmy, by the way, is in Iraq, as well. Perhaps this set of nominees will shut up those who caterwaul endlessly that old men in Washington send the children of others to die in foreign lands. That remains to be seen.)

The Obama campaign reacted immediately and dismissively:

“Today, John McCain put the former mayor of a town of 9,000 with zero foreign policy experience a heartbeat away from the presidency. Governor Palin shares John McCain’s commitment to overturning Roe v. Wade, the agenda of Big Oil and continuing George Bush’s failed economic policies — that’s not the change we need, it’s just more of the same,” said spokesman Bill Burton.

Such petulance is a stark contrast to the dignity with which the McCain campaign set aside partisanship last night and congratulated Obama on his historic nomination, as well as the grace with which Palin paid tribute to Hillary Clinton and her accomplishments upon her introduction to the nation. It will be interesting to see how the tone changes over the next few weeks, as the Obama campaign gets used to this new factor in the race.

From any perspective, this is an historic, interesting--even risky--vice-presidential choice that energizes the campaign in a way that no one has since...well, last night. It has surely been an interesting campaign season, one surprise after anther. And, today, a genuine "game-changer."

Regardless of one's party, surely we can agree (as Barack Obama might say) that it's all very compelling politics.