The Stones have used prompters for years. Their IMAX movie, released in the early 90s, has several shots where the lyrics are rolling by, and, my personal favorite, stage directions. When it was time for Keith to sing "Happy," the prompter read something like "KEITH SINGS MICK OFF STAGE." Hilarious.
At the show I saw, they had a long 'catwalk' to what turned out to be a much smaller stage out in the center of the floor. About halfway through their show, they stopped playing, walked on the catwalk to the 'ministage' and played a great set. Trying to create an intimate, small-bar feel in a 50000 seat stadium.
It worked, the crowd went wild. It must have been really cool for the folks with front row seats. And like I said, with my bird's eye view (albeit from 100 feet above!) there weren't any teleprompters.