function OnNetworkInstantiate (info : NetworkMessageInfo) {
    if (networkView.isMine)
        Debug.Log("New object instanted by me");
    else
        Debug.Log("New object instantiated by " + info.sender);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnNetworkInstantiate(NetworkMessageInfo info) {
        if (networkView.isMine)
            Debug.Log("New object instanted by me");
        else
            Debug.Log("New object instantiated by " + info.sender);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnNetworkInstantiate(info as NetworkMessageInfo):
        if networkView.isMine:
            Debug.Log('New object instanted by me')
        else:
            Debug.Log(('New object instantiated by ' + info.sender))