LucasArts has answered the following question about Knights of the Old Republic:

What kind of Force powers will be used in Star Wars: Knights of the Old Republic?

You will be able to gain access to over 50 Force powers. Some examples are Force lightning, Force push, Force wave and drain life. The Force powers have quite spectacular effects, which make them extremely satisfying to use in combat. There are also non-combat Force powers such as Force persuasion.

See the drain life Force power in action at the screenshot gallery at the Knights of the Old Republic official site.