GUESS THE JOKE'S on us.

As Sarah Palin's mystery tour rolled into Philadelphia yesterday, dozens of sweaty reporters and photographers - mostly card-carrying members of the "lamestream media" that Palin openly despises - sprang into action.

With a news chopper hovering above, they sprinted toward Independence Hall to get a glimpse of the 2008 failed vice-presidential candidate who abandoned her post as Alaska's governor in 2009 and has reinvented herself as a celebrity quasi-politician who may or may not launch a longshot bid for the White House in 2012.

The former mayor of Wasilla was practically crushed by the scrum of TV cameras and star-struck fans as she crossed Chestnut Street on her way to inspect the crack on the Liberty Bell.

But if Palin - who many political analysts doubt would make a viable candidate - isn't going to run for president, why do we care?

Is she just playing hard-to-get to boost her media profile and cash in on her skyrocketing celebrity status?

"The more confusing it becomes, the more publicity she gets in this crazy upside-down world we live in," said Franklin & Marshall College pollster G. Terry Madonna.

"It's bizarre," he said. "She's become a celebrity, a kind of rock star with no serious purpose in mind. I get no sense that anybody has a clue why they're covering this stuff."

Palin, who embarked this week on an ill-defined tour of historic sites that has drawn national media attention, shed little light on her White House ambitions yesterday:

"Don't know if I'm running yet," she said, "but having a great time on this tour."

You betcha.

That ambiguity is precisely the point, according to some political and media analysts who think that the Republican firebrand is manipulating the media to build a potentially lucrative brand name on the backs of her conservative supporters with folksy platitudes and calculated speculation about her political future.

Andrew Mendelson, chairman of Temple University's journalism department, expects this story to end with Palin - best-selling author, Fox News pundit and reality-TV star who charges six figures for speaking engagements - laughing all the way to the bank.

"This is about building up her brand and definitely mocking the mainstream media," Mendelson said. "There's an intentionality about what she's doing."

Palin, who has turned political reporters into virtual enemies of the state in the eyes of her fans, has pulled off an impressive coup with her "One Nation" bus tour, which stopped at Gettysburg and Mount Vernon, and included a dinner with Donald Trump in Manhattan.

By keeping reporters in the dark about where her entourage will stop next, Palin has manufactured so much interest that the press corps she so often criticizes is now clinging to her every word, even if the words are mostly "vagaries and generalities," Mendelson said.

It's the silver bullet of free publicity. Reporters hate being out of the loop. Pull back the information and they'll come to get it. No one wants to be scooped.

"I would say the joke is on the media," Mendelson said.

"If you didn't cover her, she could say, 'Look how liberal they are, they won't even cover me.' But by covering her, she's able to say, 'Look, they're bending over backwards to get to us, we must be relevant.'

"It's a win-win for her," he said.

Teri Adams, president of the Independence Hall Tea Party Association, was roasting in the sun yesterday, waiting for Palin to arrive.

"I think she's been teasing the press, who have been very hard on her," Adams said. "And I can't blame her.

"She's a formidable figure in politics. She's not someone that anyone should take lightly."

Political analysts aren't so sure.

"Her negatives, from a pollster's perspective, are just through the ceiling," said Christopher Borick, director of the Muhlenberg College Institute of Public Opinion. "Those are some really strong deterrents for her to run.

"If, at the end of the day, she expands her brand for commercial purposes, it's probably not a bad strategy for her," he said.

But several Palin supporters at yesterday's event say she's already got their vote.

They desperately want her to pull the trigger - and prove the media wrong by getting elected.

Elaine Couch, who calls Palin "my girl," rushed back to her Mayfair home to grab her camera and Palin buttons before heading down to Independence Hall to see the potential candidate in person.

President Obama is "a socialist," Couch said, and Palin is "for capitalism." It's that simple.

"She generates a lot of excitement," Couch said.

"Contrary to the way the media portrays her, I think she knows what she's doing and she's not afraid to speak out for what she believes in. I think we need somebody like that."

Madonna, however, has all but dismissed Palin as a viable candidate, saying she is unlikely to attract enough support from suburban voters in key states like Ohio, Pennsylvania and Florida.

"This is about celebrity and all of the perquisites that come with being a celebrity," Madonna said.

"This is about fame. It's not about a serious candidate for the presidency of the United States."