LucasArts has confirmed that the demo for Star Wars: The Force Unleashed will release for Live and PSN on August 21.
From the release:
The demo gives players a taste of one of the early levels in the game: the TIE Fighter Construction Facility, under siege by a Jedi General named Rahm Kota. The Secret Apprentice has been sent by Darth Vader to hunt down and destroy the General, but is also told that, in order to remain a secret, he is to leave no witnesses.
Also included in the demo is a tutorial intended to teach players how to use their Force Grip power.
More through the link.