Require.js plugin to detect the global jQuery version and use a local jQuery if the global version is too old.

config.js

// Map jquery module to the plugin
// Credits to jburke
// https://github.com/jrburke/requirejs/issues/451#issuecomment-8442745
require.config({
  map: {
		'*': {
			'jquery': 'jquery!'
		}
	}
});

jquery.js

define(["versionCompare"], function (versionCompare) {

	// Specify the required jQuery version here
	var jQueryVersion = '1.10';

	return {
		load: function (name, parentRequire, onLoad, config) {
			if ($ in window && versionCompare(window.$.fn.jquery, jQueryVersion, '>=')) {
				// Return global jQuery version
				onLoad(window.$);
			} else {
				// Load and use local jQuery version (of course jquery-ui can be omitted here)
				parentRequire(["lib/jquery", "lib/jquery-ui"], function (jQuery) {
					// No conflict with existing jQuery
					jQuery.noConflict();

					// More jQuery initialization (like event proxying between the jQuery versions)
					// can be put here
					// window.$: global jQuery
					// jQuery: local jQuery

					// Return local jQuery
					onLoad(jQuery);
				});
			}
		}
	};

});

versionCompare.js

define(function () {
	// versionCompare module could return a function like this:
	// http://phpjs.org/functions/version_compare/
});