As if he planned to reveal it all along, Newsom casually Twittered that his wife, Jennifer Siebel Newsom, was pregnant, after the Valleywag reported the news yesterday. In a news conference today, though, he admitted that the news didn't come out quite the way he wanted:

The mayor fielded questions about fatherhood today following a news conference about improvements to Civic Center Plaza, saying that the baby is due later this year, possibly sometime in September.

Newsom welcomed "any advice on diapers, any advice on feeding times, any advice on names," or other topics related to a new child, and said he was already receiving tips on his Twitter account....

He said some extended family members learned of the pregnancy through TV reports.

He even apologized to his Aunt Annie:

"Unfortunately, some gossip column in New York City leaked this, and so we didn't announce it in the way we intended to, but such is the life of public service," Newsom said Thursday outside City Hall. "I had to deal with my aunt. To my Aunt Annie, I apologize for you watching it on TV last night. The point being that I hadn't reached out to our extended family to let them know before everyone else found out."

("Some gossip column in New York City"? Gavin, hon, you need to brush up on your local media. Valleywag is based in San Francisco. How else would we have heard about it first?)

What better way to play the news than as benighted new father, dealing with anxious relatives and soliciting advice about diapers? It is a happy event for the Newsoms, certainly, as a family. But going into a tight race to be California's next governor, it could also spell a rebirth of his political ambitions.

Newsom, a Democrat, has declared himself a candidate for California's governor seat, a wide-open race taking place next year, since term limits are keeping Arnold Schwarzenegger from running again. A rising star in the Democratic party, Newsom has hurt himself with gaffes both personal and political.

He and his first wife, Fox News TV host kimberly Guilfoyle, divorced in 2006. While going through the divorce, Newsom had an affair with Ruby Rippey-Tourk, the wife of his campaign manager, Alex Tourk. The divorce and affair ruined Newsom's Camelot-by-the-Bay image.

His wedding last year to Siebel, a cousin of wealthy software entrepreneur Tom Siebel, was a step towards restoring his tattered image. (Google founders Larry Page and Sergey Brin ferried guests in their private jet to the wedding site on a Montana ranch.)

But then came Proposition 8, California's ban on gay marriage, a cause Newsom has championed since he defied state law in 2004 by issuing marriage licenses to gay couples (including the author of this post). At a rally, Newsom declared that gay marriage was coming to California "whether you like it or not," a sound bite Prop 8 supporters aired endlessly in TV commercials and was cited in many election post-mortems as a factor in the passage of Prop 8.

With memories of his messy personal life still fresh, and his main cause defeated in the last state election, Newsom's push for the governor's seat looked like it was off to a rocky start. In the Democratic primary, he faces California Attorney General Jerry Brown, the former Governor Moonbeam.

But political observers say Brown may strike potential voters as too old. With Newsom's wife expecting a child in the fall, he will have the perfect family-man campaign prop. What better way for a claimant to the throne to seem young and vital than to have his very own heir?

Update: The mayor's office has confirmed that the Newsoms are expecting. Spokesman Nathan Ballard said:

We are pleased to confirm that Mayor Gavin Newsom and First Lady Jennifer Siebel Newsom are starting a family. The Mayor and the First Lady are thrilled to be embarking on this adventure together, and they appreciate your good wishes.

Guess who wasn't expecting this? Gavin's dad and Jennifer's mom, both of whom told the San Francisco Examiner that their children hadn't let them in on the secret.

(Photos by Getty Images)

Mayor Newsom is on his honeymoon.

Best part? The boilerplate continues "Note: Mayor’s schedule is subject to change." Don't give up hope, ladies! (Photo by Getty/Justin Sullivan)

Yes, Jennifer is one of those Siebels — her dad, Ken Siebel, is a cousin of Tom Siebel, the founder of Siebel Systems. The father of the bride is also chairman of Private Wealth Partners, which manages a $444 million fund. But Newsom might find it difficult to pry any campaign contributions from his new father-in-law, since the elder Siebel has donated only to Republicans in national elections since 2000, including George W. Bush, John McCain and Rudy Giuliani.

Newsom did at least convince the bride's family to host the wedding in Stevensville, Montana, where the groom wore a casual linen suit and the bride wore Vera Wang and rode down the aisle bareback on a white black stallion. By far the best blow-by-blow of the nuptials was from Newsom's predecessor at City Hall, Willie Brown. Siebel and Newsom plan to tour Africa on their honeymoon — no word if they intend to indulge in the hot celebrity trend of adopting a child as a souvenir.

Being in the family way might help burnish Newsom's image after an adultery scandal in 2007 and a public admission of the entrepreneurial wine salesman's drinking problem. The timing of this marriage eerily reflects that of Newsom's first in 2001, when the then-Supervisor wed Kimberly Guilfoyle months before he announced his candidacy for mayor of San Francisco.

But the couple divorced a year after he was elected amidst talk of a new "Camelot" couple rising in the Democratic Party ranks. You can expect the eternal flame of the media's love for Newsom to be rekindled along those lines, though I doubt the newlyweds will be posing in any oil-money mansions this time around.

With Newsom now fielding an exploratory committee to run for statewide office, longtime superfan and San Francisco Chronicle blogger Beth Spotswood was generous: "I give them two years, that's my wedding gift to Gavin." Which is just long enough to last until June 8, 2010, when the votes for Governor will be tallied.

Hopefully Siebel can continue to steer clear of commenting on blogs in the meantime. Siebel's first publicity challenge will be to show up California attorney general Jerry Brown's longtime partner and current wife Anne Gust in the primary, followed by Maria Shriver, wife of California Governor Arnold Schwarzenegger. (Photo by Getty Images/Meg Smith)