Tron: The Next Day is a ten minute short that aims to fill in the gaps between Tron: Legacy and the upcoming Tron 3.
This short sheds light on the "Flynn Lives" movement and shows what happens after Sam takes over Encom at the end of Tron: Legacy. This is supposedly just one of two Tron 3 teasers on the Tron: Legacy blu-ray.
Forget all the talk about how bad video game or computer game movies are, the original Tron is well worth checking out.
News: ‘TRON: The Next Day – Flynn Lives' Revealed Leaked Online [Latino Review via io9]