Here is my script I can drop on a CharacterController or select one from the dropdown list in the inspector. I have done rudimentary testing on a rotating platform as I figured that was more of a trick than just a translating platform. To use it tag those surfaces with a "MovingSurface" tag so the OnCharacterColliderHit can find the name of the tag and implement the algorithm if the hitObject tag == "MovingSurface". Thanks to those I stood on the shoulders of to finally get this. Now for coffee.

var myCharacterController : CharacterController;
private var activePlatform : Transform;
private var hit : ControllerColliderHit;
private var activeGlobalPlatformPoint : Vector3;
private var activeLocalPlatformPoint : Vector3;
private var activeGlobalPlatformRotation : Quaternion;
private var activeLocalPlatformRotation : Quaternion;
var tagName : String;
private var moveDirection = Vector3.zero;
private var grounded : boolean = false;

function FixedUpdate () {
    if (tagName != "MovingSurface") 
    {
    	activePlatform = null;
    	lastPlatformVelocity = Vector3.zero;
    }
    if (tagName == "MovingSurface") 
    	{
    	if (grounded) {
    		// We are grounded on a Moving Surface, so recalculate move direction directly from axes
    		moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
    		moveDirection = transform.TransformDirection(moveDirection);// Move the controller
    		var controller : CharacterController = GetComponent(CharacterController);
    		var flags = controller.Move(moveDirection * Time.deltaTime);
    		grounded = (flags & CollisionFlags.CollidedBelow) != 0;
    		//Keep moving (?) by getting the spped var from the FPSWalker CC script or whatever you are using 
    		moveDirection *= FPSWalker.speed;

    	}
    var calculatedMovement = moveDirection * Time.deltaTime;
    	// Moving platform support
    	if (activePlatform != null) {
    		var newGlobalPlatformPoint = activePlatform.TransformPoint(activeLocalPlatformPoint);
    		var moveDistance = (newGlobalPlatformPoint - activeGlobalPlatformPoint);
    		transform.position = transform.position + moveDistance;
    		lastPlatformVelocity = (newGlobalPlatformPoint - activeGlobalPlatformPoint) / Time.deltaTime;
    		// If you want to support moving platform rotation as well:
    		var newGlobalPlatformRotation = activePlatform.rotation * activeLocalPlatformRotation;
    		var rotationDiff = newGlobalPlatformRotation * Quaternion.Inverse(activeGlobalPlatformRotation);
    		transform.rotation = rotationDiff * transform.rotation;
    		}
    		else
    		{
    			lastPlatformVelocity = Vector3.zero;
    		}
    		//Controller Move  takes place here 
    		collisionFlags = myCharacterController.Move (calculatedMovement);
    		// Moving platforms support
    	if (activePlatform != null) {
    		activeGlobalPlatformPoint = transform.position;
    		activeLocalPlatformPoint = activePlatform.InverseTransformPoint (transform.position);
    		// If you want to support moving platform rotation as well:
    		activeGlobalPlatformRotation = transform.rotation;
    		activeLocalPlatformRotation = Quaternion.Inverse(activePlatform.rotation) * transform.rotation;
    		}
    }
}

function OnControllerColliderHit (hit : ControllerColliderHit) {
    // Make sure we are really standing on a straight platform
    // Not on the underside of one and not falling down from it either!
    if (hit.moveDirection.y < -0.9 && hit.normal.y > 0.5) {
        activePlatform = hit.collider.transform;
        tagName = hit.collider.tag;
    }
}

See Question 694 for several solutions.