yes, if i have sound on through the widget, i get the sound and vibrate, and if i set the widget to vibrate, there's no sound, just vibration, and if i set it to silent, i just get the notification in the notification bar and a blinking light if applicable.
dang i keep editing, but the main thing is if you don't set the vibrate in notifications for each thing individually, it won't. For example, i don't have gmail set to make sound or vibrate, because i really don't care that much when i get emails, so my gmail never vibrates or makes sound no matter what.