// Calculates the angle (degrees) between
// the rotation of this transform and target.

var target : Transform;

function Update () {
    var angle : float = Quaternion.Angle(transform.rotation, target.rotation);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public Transform target;
    void Update() {
        float angle = Quaternion.Angle(transform.rotation, target.rotation);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public target as Transform

    def Update():
        angle as single = Quaternion.Angle(transform.rotation, target.rotation)