For those who really like to tinker, iOS5 for the iPhone introduced the ability to change the default vibration pattern for each address book contact.  Here are the steps:

  • Go to Settings->General->Accessibility and turn on Custom Vibrations
  • To change a vibration pattern for a contact, edit the contact entry and select the vibration setting (just below ringtones).  You can select a different pattern or select "Create New Vibration".
  • Use the screen to tap out a new pattern and select Save.
  • You can create a new pattern directly from the Sounds section under Settings.