output.log

$ node test.js 
Express app started on port 3000
Uploading: %1
/Users/bryce/Projects/app/test.js:30
      next(err);
      ^
TypeError: object is not a function
    at Object.CALL_NON_FUNCTION (native)
    at /Users/bryce/Projects/app/test.js:30:7
    at IncomingForm.<anonymous> (/Users/bryce/.node_libraries/.npm/formidable/0.9.11/package/lib/formidable/incoming_form.js:96:9)
    at IncomingForm.emit (events:31:17)
    at IncomingForm._error (/Users/bryce/.node_libraries/.npm/formidable/0.9.11/package/lib/formidable/incoming_form.js:225:8)
    at IncomingForm.write (/Users/bryce/.node_libraries/.npm/formidable/0.9.11/package/lib/formidable/incoming_form.js:123:10)
    at IncomingMessage.<anonymous> (/Users/bryce/.node_libraries/.npm/formidable/0.9.11/package/lib/formidable/incoming_form.js:73:12)
    at IncomingMessage.emit (events:31:17)
    at HTTPParser.onBody (http:100:23)
    at Stream.ondata (http:763:22)

test.js

/**
 * Module dependencies.
 */

var express = require('express')
  , form = require('connect-form');

var app = express.createServer(
  // connect-form (http://github.com/visionmedia/connect-form)
  // middleware uses the formidable middleware to parse urlencoded
  // and multipart form data
  form({ keepExtensions: true })
);

app.get('/', function(req, res){
  res.send('<form method="post" enctype="multipart/form-data">'
    + '<p>Image: <input type="file" name="image" /></p>'
    + '<p><input type="submit" value="Upload" /></p>'
    + '</form>');
});

app.post('/', function(req, res, next){

  // connect-form adds the req.form object
  // we can (optionally) define onComplete, passing
  // the exception (if any) fields parsed, and files parsed
  req.form.complete(function(err, fields, files){
    if (err) {
      next(err);
    } else {
      console.log('\nuploaded %s to %s'
        ,  files.image.filename
        , files.image.path);
      res.redirect('back');
    }
  });

  // We can add listeners for several form
  // events such as "progress"
  req.form.on('progress', function(bytesReceived, bytesExpected){
    var percent = (bytesReceived / bytesExpected * 100) | 0;
    process.stdout.write('Uploading: %' + percent + '\r');
  });
});

app.listen(3000);
console.log('Express app started on port 3000');