There may be a case where you want your application to cause the phone to vibrate. For example, if while playing a game you do an invalid action. Vibrating the phone will be a certain way to get their attention. I wouldn’t over use it and I recommend you give the users the option to disable it in your settings.
Doing so is very easy:
VibrateController vibrate = VibrateController.Default;
That’s it! You can mess with the timespan but 200 MS seems adequete.