The image sends on odd message for a CEO, regardless of gender, said Dan Schawbel, author of "Promote Yourself: The New Rules For Career Success" and the managing partner of Millennial Branding, a Gen Y research and consulting firm.
"It comes off as if she's on vacation, she's relaxing while everyone else is doing work," Schawbel said, noting it's especially bad since Mayer looks like she's reclining in her backyard and she famously banned employees from working from home.
(Read more: Working from home? Your boss may be spying on you)
The tablet device in her hand has a close-up image of her face, which Schawbel said may come off as narcissistic and fake. "On the picture in her iPad, she doesn't even look real," he said.
Schawbel said he was puzzled why she would pose for the picture. "I think a lot of people who are powerful just want the publicity. You're probably not going to see a male CEO turn downGQ. Maybe she's doing it because she wants to make Yahoo! look cool, with the iPad?"
Yahoo! did not respond to requests seeking comment about the picture, but Yahoo! Finance Senior Editor Mike Santoli appeared on CNBC on Friday and responded to a question about whether this if the new public-relations standard for the modern CEO.
"I cannot speak to my company's PR strategy but honestly I actually think that most of the attention is incoming," Santoli said. "I think it's thrust out there, people are interested in somebody her age going from Google and taking over, you know, this company that really had been kind of set aside for a while."
(Read more: How Marissa Mayer prevents work burnout)
Mayer, who was the 20th employee on staff at Google, was hired in July 2012 to lead the turnaround of Yahoo!. Since then, Yahoo! has acquired Tumblr, Summly, Qwiki and more than a dozen other firms. She also ended the company's relaxed work-from-home policy and extended maternity leave benefits.
She's certainly not the first prominent woman to get the Vogue treatment. Sen. Kirsten Gillibrand, D-N.Y., First Lady Michelle Obama, International Monetary Fund Managing Director Christine Lagarde and Rep. Tulsi Gabbard, D-Hawaii, have appeared in past issues.
"Marissa Mayer's success, particularly in the male-dominated world of tech, is fascinating to women," a Vogue representative told CNBC in an email. "She has been a target of such scrutiny for her work/life choices and is being watched so closely at Yahoo that she was an obvious choice for us to learn more about and understand the woman behind the public persona."
A 2009 Vogue profile called her "possibly the world's most poised and powerful information guru."
The September issue story, written by Jacob Weisberg, editor-in-chief of the Slate Group, offers a glossy view of her career and fashion choices.
Since this is Vogue, it hits her fashion chops rather early in the story (right after it mentions she is "effortlessly articulate" when talking technology but more like Alicia Silverstone in "Clueless," when it comes to discussing business.)
"(S)he is an unusually stylish geek. The day we had that conversation in her white, glossy, minimally appointed office in Sunnyvale, California, she was wearing a red Michael Kors dress with a gold belt and a brown Oscar de la Renta cardigan. This cashmere bolero is her work uniform—she has the same one in ivory, navy, black, hot pink, teal, red, and royal blue, and adds new colors every season."
(Read more: Dan Loeb and Yahoo's Mayer have a falling out)
For a Friday in August, reaction on Twitter was generally subdued.
"Seriously. Where of my glamour shots of Sergey Brin, Tim Cook, Jeff Bezos and Steve Ballmer?" asked Jamelle Bouie of The Daily Beast.
"Marissa Mayer appears to be nerdy career-obsessed Barbie, which is, truly, the life I always imagined for my dolls," said Shane Ferro of Reuters.
And from Will Alden at The New York Times' Deal Book, "Yahoo $YHOO up 1.25% on CEO's Vogue shoot."
—By CNBC's Amy Langfield. Follow her on Twitter
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