"I am so honored to help introduce this year's nominees for Best Picture and to help celebrate the movies that lift our spirits, broaden our minds and transport us to places we have never imagined," she said last Sunday for the last category of the broadcast as the clock inched toward midnight on the East Coast.
After Nicholson read the nine nominees, Obama opened the envelope and announced "Argo," the tale of the rescue of six U.S. diplomatic employees holed up in the Canadian Embassy in the first months of the takeover of the U.S. Embassy in Tehran by anti-government militants.
"Argo" producer-director-director Ben Affleck said he was stunned by the move, Fox News reported
"I was asking people, 'Was that Michelle Obama?' It was a huge honor, and the fact she was surrounded by servicemen and women," Affleck said. "It was very cool."
Others, however, didn't think it was cool -- with a few shaking their heads.
"This makes no sense. It adds nothing to the show," Fox quoted an industry expert as saying.
Scores of other viewers gave Obama props, calling her appearance via satellite "amazing" and "show stealing" -- placing her and her gown by Indian-born American designer Naeem Khan at the top of the Oscars best dressed list.
Several conservative bloggers took the first lady to task for not properly recognizing the military personnel in the room with her, Politico reported.
"The first lady was flanked by several members of the U.S. military during her satellite appearance from The White House to announce the Best Picture winner, and she failed to acknowledge their presence or their heroism," Breitbart.com's Christian Toto wrote. "Nor did Obama name-check Best Picture nominee 'Zero Dark Thirty,' the film detailing the successful hunt for Osama bin Laden, arguably her husband's finest achievement in his four-plus years in office."
Conservative columnist Jennifer Rubin said Obama went too far, making "both the president and the first lady seem small and grasping," NBC News said.
Obama hasn't been afraid of promoting through television and personal appearances the projects she holds dear: advocating healthy lifestyles while tackling childhood obesity through "Let's Move!" and helping military families in "Joining Forces."
Last week she traveled the United States to promote the third anniversary of her "Let's Move!" initiative to fight childhood obesity. Two videos she released last week with Sesame Street denizen Big Bird highlighted her efforts to encourage kids to eat healthy and become more active.
Obama likely is trying to nail down a second-term agenda that won't distract from her husband's, but is probably feeling a confidence in her role that may not have been present in her first term, Anita McBride, chief of staff to Laura Bush, told NBC News.
"The difference between a first term and a second term really is the fact that you've got your grounding," she said. "All of the lessons learned of a first term, now you can pick up and have the freedom to really act."
"The one rule that Michelle Obama always follows is that she never wants to distract from her husband's agenda," said New York Times journalist Jodi Kantor, author of the book "The Obamas."
"It's possible that she might address tougher, more controversial issues, but I do not believe based on what aides have told me that she would do it if she thought that she was going to cause a furor and distract from what her husband was trying to get done," Kantor said.
Second-term first ladies usually feel freer to speak more forcefully about issues, Katherine Jellison, a history professor at Ohio University, told NBC News.
"You don't see them deviating greatly from their interests or public causes from their first terms, but there's a general sense of being more relaxed in advocating the more controversial aspects of those projects," she said.
Witness Laura Bush, who stayed in the background during George W. Bush's first term -- but once he won a second term, she surprised many by speaking out against the deplorable treatment of Afghan women in their country.
She also spoke out against the repressive conditions in Myanmar, championing the release of the recently freed democracy activist Aung San Suu Kyi.
"Mrs. Bush felt a certain amount of freedom because she knew they didn't have to face re-election again," Myra Gutin, a first ladies expert, told NBC. "These were definitely issues more political in nature, but at that point, a second-term first lady will ask, 'Is it going to cost my husband political capital?' Eh, maybe, but he's not going to be voted out of office."
Obama last fall said she learned to avoid controversy through the years.
"I think that I am strategic," she said on NBC's "Today." "I feel like I have to be strategic because I want to be sure that the things I do further my husband's administration."
Gutin said she was surprised the first lady hasn't tackled race.
"There's always that race consciousness there, but Mrs. Obama has really gone beyond that and has made it a non-issue," she said.
But race does play into what kind of legacy she will leave behind, said Watson.
"She is the first African-American first lady and therefore it is something special. A thousand years from today, you'll talk about Martha Washington and Eleanor Roosevelt, and you'll talk about Michelle Obama," Watson told NBC. "She's making history and so she's got to be concerned about her legacy."
Tina Tchen, Obama's chief of staff, said the first lady may seem more visible because of the president's re-election campaign, but her recent appearances and efforts really don't reflect any change from the first term.
"I guess I would say that the level of activity over the course of the last term to now has been pretty consistent," Tchen said.
In an interview published in Diplomatic Courier magazine, McBride said the unifying characteristic of all first ladies was dedication to their husbands' success.
"Every problem comes to the desk of their husbands, and they take the criticisms and successes of their husbands to heart," she said. "They also realized that they have a platform. First ladies have a complicated position and can make it into what they want it to be; but you have to remember -- they can be an advocate for policy but not a policymaker."