Miss Pillowlips, aka Angelina Jolie (search), arrived first at the Sheraton New York Hotel and Towers.
She was photographed chatting with Norwegian President Kell Magne Bondevik before sauntering over to a morning discussion on poverty.
Her good friend, U.N. Millennium Project director Jeffrey Sachs, spoke at the talk.
After the panel discussion began — which unlike others was closed to photographers — Brad Pitt (search) quietly slid in and sat on the opposite side of the room from his unconfirmed girlfriend.
Their relationship, which began while they were filming "Mr. & Mrs. Smith," is regarded as the catalyst for the demise of Pitt's marriage to Jennifer Aniston.
But they're coy about their connection and have not admitted to a love affair — despite being spotted vacationing together and posing for artsy photographs as a mock suburban husband and wife in W magazine.
When Sunday's lecture ended, Pitt, who had attended the conference Friday as well, apparently left through a side door.
The three-day conference — which ended Sunday — was organized by Clinton to highlight global issues such as poverty and the environment.
Attendees included heads of state, business leaders and celebrities such as Mick Jagger, Bono, Oprah Winfrey and Barbra Streisand.