Remember the pretty little Chinese girl who sang her little heart out at the opening ceremony while impressive fireworks kicked off around Beijing to mark the opening of the Olympics? Well she was miming while a not quite so pretty little Chinese girl sang backstage...and the fireworks weren't actually real, they were computer generated.
source: http://news.bbc.co.uk/2/hi/asia-pacific/7556058.stm
source: http://news.bbc.co.uk/2/hi/asia-pacific/7556058.stm