[iMore.com]

By default your iPhone uses two quick vibration pulses for a text message and a continuous steady pulse vibration for incoming calls. All other Notification Center alerts receive a single vibration. But what if you want something different so you can easily tell what kind of notification you're receiving without even looking at your iPhone? As it happens, you can do just that by creating and assigning your own vibration patterns. Here's how:

Full story from the iMore Blog...