What is your player? Is the player another rigidbody, or is it a CharacterController or a static collider using transform.Translate for movement? Static colliders won't cut it here- you should at least use a kinematic Rigidbody here. The best way is to make the player a non-kinematic rigidbody (preforably with freezeRotation on so that you don't roll everywhere) so that it can interact with other rigidbodies properly.

FPScontroller is the one that uses controller.Move(moveDirection) using a charController, right? CharConts purposely do not push or even hit other objects. They sort of see that they would hit something, not in the physics engine, and slide around before technically colliding.

The special http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.OnControllerColliderHit.html was created for this. That page has an example of how to "build" a push. Since it's code, you can tweak/redo it all you like (for example, to push away from you instead of directly forwards.)