Jay Z and Beyonce weren't scheduled to perform at Coachella Music and Arts Festival in Indio, Calif., over the weekend, but stepped onstage anyway for a couple of surprise cameos. Beyonce didn't sing a note on Saturday, but joined sister Solange Knowles for a choreographed dance duet to "Losing You." "Give it up for my favorite dancing partner and my favorite person in the world, my sister, Beyonce," Solange told the audience. Nas, who settled a feud with Jay Z back in 2005, invited the Magna Carta Holy Grail rapper onstage to perform their 1996 collab "Dead Presidents II."