Yes, her husband was on that most-influential list, too, as well as 98 other movers and shakers in the worlds of politics, technology, business, fashion, science, television, film and music.
But it was clearly Mrs. Obama, dressed in a long black gown with a corset bodice and jet beads draped around her neck, whom the crowd wanted to see.
And it was a powerful crowd that stood to applaud her entrance, including fellow honorees Oprah Winfrey, Barbara Walters and her cohorts from "The View," financial analyst Suze Orman, fashion designer Stella McCartney, and the guys who invented Twitter.
Not on the honoree list but also attending: Diane Sawyer and Charlie Rose. Actors Claire Danes and Hugh Dancy, Kate Hudson and Liv Tyler. Director Judd Apatow, "Saturday Night Live" producer Lorne Michaels, conservative pundit Ann Coulter.
In her speech, Mrs. Obama spoke of the importance of public service in her own life, and then announced that the president's budget proposal for next year will include $50 million to help promote national service and advise nonprofit groups.
The money would be startup capital for the new Social Innovation Fund, she said, designed to help nonprofits think about service in new ways and approved by Congress as part of a national service law.
"The idea is simple: Find the most effective programs out there and then provide the capital needed to replicate their success in communities around the country," the first lady said.
"By focusing on high-impact, results-oriented nonprofits, we will ensure that government dollars are spent in a way that is effective, accountable and worthy of the public trust."
Earlier Tuesday, Mrs. Obama addressed diplomats and staff members at the U.S. Mission to the United Nations, thanking them for promoting her husband's new foreign policy of global engagement.
As the swine flu outbreak demonstrates, she said, "we know now that we cannot wall ourselves off from issues that are challenging our neighbors."
"This new policy recognizes that America's future is intricately linked to the rest of the world, that the threats facing the global community know no borders, and no single country can tackle them alone," Mrs. Obama said.
It sounded, though, like the highlight of her day - and to take her at her word, perhaps even her life as first lady so far - was the appearance with Elmo and Big Bird.
"I never thought I'd be on 'Sesame Street' with Elmo and Big Bird and I was thrilled," she told the crowd at the mission. "I'm still thrilled. I'm on a high."
"I think it's probably the best thing I've done so far in the White House."
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