Now might be a good time for Madonna to undergo one of her trademark transformations, morphing from her current persona of an iron-pumping gym rat into, say, a voluptuous and va-va-voomy pinup from Hollywood's golden age.

The pop icon didn't exactly dress to impress on Friday as she exited the Kabbalah Centre in New York amid a pack of paparazzi, stepping out in a worn gray T-shirt and matching sweat-shorts, an ensemble that highlighted her bulging, walnut-crushing arms, super-sinewy figure and makeup-free, hollow-cheeked face.

Perhaps her angular look (or, as the New York Daily News less kindly puts it, her "frazzled" and "frighteningly skinny" look) is the result of working out extra-hard to get ready for her about-to-launch Sticky & Sweet tour. Or maybe she's been feeling the burn to relieve some of the stress caused by speculation over the state of her union to Guy Ritchie (not to mention the rumors -- adamantly denied -- of her supposed "affair of the heart" with New York Yankees star Alex Rodriguez) and her brother's just-released tell-all.

Guy and Madonna at the Kabbalah Center in New York on July 11

Ritchie couldn't escape the whispers as he stumped for his upcoming flick "RocknRolla" at the San Diego Comic-Con last week.

The filmmaker assured People that everything is just fine in their seven-plus years of marriage, although he couldn't resist adding the cheeky qualifier, "as far as I'm aware of."

Meanwhile, the director's leading man, Gerard Butler, reveals that he, like Justin Timberlake before him, was ordered to bare his butt for a B-12 shot-wielding Madonna.

"I was sick, and she was a nurse basically," explained the beefy actor (via Us). "Guy introduced me to her and she said, 'You're the sick one?' and I said, 'Yes.' Well, she was amazing. She just said, 'Drop your pants.'"

Recalls Butler, "I stood there with my little bottom out, and she gave me a shot in the bum!"

Too bad the posterior piercing was all for naught.

"It didn't work at all -- I got more sick!" he says. "But I appreciated the effort."

Speaking of making an effort, the London Sun claims Madonna and Guy plan to renew their marital vows in front of family and friends -- along with a pair of rabbis -- during a Kabbalah-themed soiree at their English estate, a ceremony that would take place right around Madonna's 50th birthday on Aug. 16.

"It's a very important dinner for them -- they want everyone to know they are still in love," a source maintains to the tabloid. "[Madonna] and Guy are making speeches in front of the rabbis. Knowing Guy, he'll have a laugh with it and they'll make light of the whole thing. But there is a serious message."

But her rep dismisses the rumblings of a rabbi-witnessed reaffirmation of their mutual affection, telling "Entertainment Tonight" the story is "complete fiction."

Also being shot down is a New York Post report that alleges the Big M had a hand in penning brother Christopher Ciccone's bombshell-light memoir, "Life With My Sister Madonna."

"The supposed scandal about Christopher Ciccone's book is bull[bleep]," a source snipes to the paper. "She actually ghost-wrote parts of it with him, the way Princess Diana helped Andrew Morton write his book on her. That's why there's nothing too devastating in Chris' book. He's mean to others, but not so much to his sister."

Not so, says her vigilant if vacation-needing flack, who eye-rolls to "Extra" that this is "the most ridiculous of all the Madonna rumors." 

Besides, Ciccone doesn't exactly give his onetime meal ticket a tongue bath, as evidenced by this passage: "Over the years, my sister's sense of loyalty and fairness has clearly been eroded by the adulation, the applause and the sense of entitlement."

Last month, Madonna's mouthpiece told the AP she found Ciccone's decision to pen a tell-all tome "very upsetting," and pointed out that the siblings "do not have a close and loving relationship."

And in still more rumor mill muttering, the London Sun contends that Madonna has been "grumpy" while rehearsing for her tour, to the point where she supposedly gave a few dancers the heave-ho and tossed a hissy fit over the elevator-set video segment Britney Spears recently shot for the tour.

"Britney looks amazing in the video but [Madonna] watched it and told them to take it out because she hated it," charges a snitch. "It was a scene where Britney was pretending to rip her own hair out."