ExpressJS so simple it should work but of course it does not.

config.js

require.paths.unshift('./node_modules')

var express = require('express')
,   app = express.createServer()
,   store = require('connect-redis') 


app.configure(function(){
    app.use(express.methodOverride())
    app.use(express.bodyParser())
    app.use(app.router)
    app.use(express.cookieParser())
    app.use(express.session({ secret:'none', store: new store}))
})

app.configure('development', function(){
    app.use(express.errorHandler({ dumpExceptions: true, showStack: true }))
    app.use(express.logger())
})

app.configure('production', function(){
    app.use(express.errorHandler());
})

exports.app = app

server.js

var app = require('./config').app
,   port = process.env.PORT || 4000


app.get('/', function (req, res) {
    console.log(req.session) // undefined
    res.render('index.html.ejs', {req: req})
})


app.listen(port)
console.log('Listening on port ' + port)

your middleware config makes no sense.. having methodOverride above bodyParser also makes no sense.. it needs req.body to check for req.body._method, and both cookieParser/session should be above app.router. also having logger() at the bottom will not work (typically it's at the top) because it wraps res.end() to provide response time data...