The trailer for The Invention of Lying, an upcoming flick written by, directed by, and starring Ricky Gervais.
The world of the movie is one in which everyone tells the truth all the time...until Gervais invents lying. It also stars every other Hollywood actor and comic in the world, including Jennifer Garner, Jason Bateman, Patrick Stewart, Jeffrey Tambor, Tina Fey, Christopher Guest, Rob Lowe, Louis C.K., and John Hodgman. (You know it's quite an august list when you have to stick "and John Hodgman" on the end of it.)