The Hulu Plus app for the iPhone, iPad, or iPod Touch portable devices can output video to a TV or external display using the Apple AirPlay feature of the Apple TV.

In order to use AirPlay with your portable iOS device, you must first connect your Apple TV and the portable device to the same Wi-Fi network. Please note that AirPlay will not work with devices other than the Apple TV.

Once that is done, you can enable AirPlay on your device by following these steps:

1. On your iPhone, iPod Touch, or iPad, double-press on the home button.  You should see a row of currently-running apps.
2. Swipe the bottom row of icons to the right twice.  The first time you swipe, you should see your music controls.  On the second swipe you should see a volume control. If your Apple TV is connected to the same Wi-Fi network, you should also see an AirPlay icon -- it looks like a small television set.
3. Tap the AirPlay icon. You should see all the available devices that support AirPlay, such as your Apple TV.
4. Select your Apple TV from the list of devices.

Your TV will now display the Hulu Plus application, and you can now play video from the Hulu Plus app to your TV.