One of the earlier keyboard hacks that was released for the iPhone was the ability to use Emoji, or ’emoticons’, when typing.
Emoji allowed iPhone owners to send each other little smiley faces and other unique characters in emails, SMS, notes, and more.
The stock iOS 4.0/4.0.1 firmware once again continues to disable Emoji. So, do the following steps to enable Emoji on your iOS 4.0/4.0.1 device:
1.) Install Emoji Free from the App Store [link].
2.) Run the app on your iOS 4.0/4.0.1 device. Tap on “Let’s do this” and exit the app when prompted.
3.) On your device, go to Settings > General > International > Keyboards > Add New Keyboard and search for “Emoji”
4.) Tap on the “Emoji” selection and power cycle your device (turn the device off and then on again).