GeometryUtility.CalculateFrustumPlanes  

// Creates 6 planes that represent the camera frustrum.

private var cam : Camera;
private var planes : Plane[];

function Start() {
    cam = Camera.main;
    planes = GeometryUtility.CalculateFrustumPlanes(cam);

    for(var i : int = 0; i < planes.Length; i++) {
        var p : GameObject = GameObject.CreatePrimitive(PrimitiveType.Plane);
        p.name = "Plane " + i.ToString();
        p.transform.position = -planes[i].normal * planes[i].distance;
        p.transform.rotation = Quaternion.FromToRotation(Vector3.up, planes[i].normal);
    }
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    private Camera cam;
    private Plane[] planes;
    void Start() {
        cam = Camera.main;
        planes = GeometryUtility.CalculateFrustumPlanes(cam);
        int i = 0;
        while (i < planes.Length) {
            GameObject p = GameObject.CreatePrimitive(PrimitiveType.Plane);
            p.name = "Plane " + i.ToString();
            p.transform.position = -planes[i].normal * planes[i].distance;
            p.transform.rotation = Quaternion.FromToRotation(Vector3.up, planes[i].normal);
            i++;
        }
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    private cam as Camera

    private planes as (Plane)

    def Start():
        cam = Camera.main
        planes = GeometryUtility.CalculateFrustumPlanes(cam)
        i as int = 0
        while i < planes.Length:
            p as GameObject = GameObject.CreatePrimitive(PrimitiveType.Plane)
            p.name = ('Plane ' + i.ToString())
            p.transform.position = ((-planes[i].normal) * planes[i].distance)
            p.transform.rotation = Quaternion.FromToRotation(Vector3.up, planes[i].normal)
            i++