Boilerplate code for a Greasemonkey script which reuses the jQuery from the page it's attached to.

Greasemonkey-jq-boilerplate.js

var jQuery, $ = null;

function addJQuery(callback) {
	var p = null;
	
	if(window.opera || window.navigator.vendor.match(/Google/)) {
		var div = document.createElement("div");
		div.setAttribute("onclick", "return window;");
		p = div.onclick();
	}
	else {
		p = unsafeWindow;
	}
	
	jQuery = $ = p.jQuery.noConflict();
	callback();
}

function handler_examplePage1() {
	// You can use both $ and jQuery
	alert('Page 1');
}

function handler_examplePage2 {
	alert('Page 2');
}

// Apply script modifications
(function(href) {
	var pageModifiers = {
		'example/page-1': handler_examplePage1,	// Will be called if page URL contains example/page2
		'example/page-2': handler_examplePage2
	}
	
	for(var pageId in pageModifiers) {
		if(href.lastIndexOf(pageId) > 0) {
			addJQuery(pageModifiers[pageId]);
			return;
		}
	}
})(window.location.href)