Lady Gaga in 2011. (Michael Buckner/Getty Images)

The buzz was true: Lady Gaga did indeed come to town to perform at the final inaugural ball, the Tuesday night bash for campaign staffers at the Washington Convention Center. Following remarks from President Obama and Joe Biden, Gaga took the stage, looking kind of like a robot swan in a Nancy Sinatra wig (judging from the many photos posted online) and sang a few of her hits — “Born This Way,” “Edge of Glory.” And then, the unexpected surprise: Tony Bennett joined her for a duet on “The Lady is a Tramp.” (They first recorded the Rodgers & Hart classic together in 2011.) And then they were off, Gaga politely explaining that she had to make it to a concert in Phoenix tomorrow.

Read also at Post Politics: At inaugural ball, Obama honors deceased staffer, 1/23/12

More Reliable Source: Rahm Emanuel’s after-party; Beyonce; White House after party; Ashley Judd; celebrity sightings