"Giacchino also composed the score for next year's short (in front of Brave). Too bad he doesn't do Brave itself.
After Cars 2 scoring sessions [were] done, the musicians stayed put and recorded the music for that short. It's a nice and clever short, very well-put together, and needless to say, Giacchino's music for the short is very fitting."I can't independently confirm this, so treat it as a rumor for now. But something tells me it's for real.
Update: Confirmed. The title of the short is La Luna.
(Updated May 5)