JSDeferred 使って書き直さないとちゃんと動かないんじゃないかな？

なかったことにしたい.user.js

// ==UserScript==
// @name           FaceBook Auto Poke
// @namespace      ns.aerith.sc
// @include        http://www.facebook.com/*
// ==/UserScript==

(function () {
	var target_id = 'pagelet_netego_pokes';
	var container = document.getElementById(target_id);

	function onPokeBackNodeInserted (event) {
		var element = event.target;
		var links = element.getElementsByTagName('a');

		for (var i= 0; i < links.length; i++) {
			var link = links[i]
			if (link.getAttribute('rel') == 'async-post' && link.className.length == 0) {
				simulateClicking(link);
			}
		}

	}

	function onPokeDialogNodeInserted (event) {
		var element = event.target;
		if ((element.className || '').match(/\bgeneric\_dialog\b/)) {
			element.addEventListener('DOMNodeInserted', onPokeButtonNodeInserted, false);
		}
	}

	function onPokeButtonNodeInserted (event) {
		var element = event.target;

		var buttons = element.getElementsByTagName('input');
		for (var i= 0; i < buttons.length; i++) {
			var button = buttons[i];
			if (button.type == 'button') {
				simulateClicking(button);
				break;
			}
		}
	}

	function simulateClicking(element) {
		var event = document.createEvent("MouseEvents");
		event.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
		element.dispatchEvent(event);
	}

	if (container != null) {
		window.addEventListener('DOMNodeInserted', onPokeDialogNodeInserted, false);
		container.addEventListener('DOMNodeInserted', onPokeBackNodeInserted, false);
	}
})();