Before Tron: Legacy came out, I saw this trailer: http://www.youtube.com/watch?v=a1IpPpB3iWI
I don't recall seeing it in the movie, was it deleted, or abandoned?
I'm pretty sure that's one of their special effects tests/teaser trailers. I recall hearing about Disney showing something like this off at conventions long before the movie came out. Note the substantial differences between how the programs look there compared to the finished movie, and the date the video was posted.