async.js

function parseThatXML(content, rootElement) {
    var result = {}, $el = $(content).find(rootElement);
            
    $el.children().each(function() {
        result[this.nodeName] = $(this).text();
    });
    return result;
}

var Zap = {
    customers_post_poll:function(bundle, cb) {
        var customers = $.parseXML(bundle.response.content).getElementsByTagName('Customer');

        var lookupCustomers = _.map($(customers), function(element) {
            var CustomerID = $(element).find('CustomerID').text();
            var req = bundle.request;
            req.url = req.url + '/'+ CustomerID 
            return function(next) {
                z.request(req, function(err, response) {
                    var customer = parseThatXML($.parseXML(response.content), 'Customer')
                    next(err, customer);
                });
            }
        });
        async.parallel(lookupCustomers, function(err, results) {
            cb(err, results);
        })
    }
};