In U2's new video "Window In The Skies", there is a glimpse of Björk, taken from the Coachella concert in june 2002. You can glimpse that at YouTube.

The video for Window in the Skies, the new single released on January 1st, can safely be described as ‘legendary’. A work of brilliant editing, the video stars a dazzling cast of rock’n’roll icons from Elvis Presley to Marvin Gaye, Patti Smith to Frank Sinatra.. and dozens of others. And everyone is on on lead vocals. As for U2 themselves – you’ll be hard pressed to spot them. (But you just might). / u2.com