The upcoming story driven thriller from Quantic Dream, Beyond: Two Souls has been confirmed to have a demo which will release this October 1st. The news was confirmed by Playstation Blog who say the demo will feature two scenes from the final game:
Jodie & Aiden: Join a very young Jodie as she takes part in an experiment at the Department of Paranormal Activities. As officials put her abilities to the test, you take charge of a mysterious, invisible entity.
Hunted: Skip forward a number of years and help Jodie escape the clutches of government agents as the mysterious entity unleashes its truly astonishing powers.
Source: Playstation Blog