One of the ‘hidden’ new feature in iOS 5 is also one of our favorite. You can now define your own keyboard shortcuts in iOS 5.
To setup keyboard shortcuts, go to Settings > General > Keyboard. Tap “Add New Shorcuts…” at the bottom of the screen to add a new shortcut. Enter the phrase and a shortcut code and tap “Save”. With the above example shortcuts, when you enter the shortcut code “iii”, iOS 5 will auto-correct it to the phrase “I Love You”.