gistfile1.js

var app = require('express').createServer()
  , io = require('socket.io').listen(app);

io.configure(function () { 
  io.set("transports", ["xhr-polling"]); 
  io.set("polling duration", 10); 
});

var port = process.env.PORT || 3000;
app.listen(port);

app.get('/', function (req, res) {
  res.sendfile(__dirname + '/index.html');
});

io.sockets.on('connection', function (socket) {
  socket.broadcast.emit('new_user');
  socket.emit('new_user');
  socket.on('send_message', function (data) {
    socket.broadcast.emit('new_message', data);
    socket.emit('new_message', data);
  });
});