Most genius musicians were not the literate to music notes. However in 2011, thanks to the folks at Kawai, there is an app that make playing notes easy. The Gakufu Camera is only available in the Japanese App Store. Basically this app scans the music notes, then play the melody of the notes scanned.
I hope this app come to America and SOON.
The video below is not in English, but you should get the idea.