http://localhost:8081/chef?type=json

chef.js

    app.get('/chef', function(req, res) {
        var conf = appUtil.parseConfig();
        appUtil.getChefNodes(function(result) {
            if (req.query.type && (req.query.type == 'xml')) {
                res.set('Content-Type', 'text/xml');
                res.render('xml.ejs', {baseUrl: 'http://localhost:8080', user: conf['chef']['node_name'], org: conf['chef']['organization'], nodeItems:result});
            } else if (req.query.type == 'json') {
            	res.set('Content-Type', 'application/json');
				res.json('nodeItems:result');
            } else {
                res.render('chef.ejs', {user: conf['chef']['node_name'], org: conf['chef']['organization'], nodeItems:result});
            }  
        });  
     });

oh, line 9, should be res.json(result);