I had the vibration just like you. Ever notice your passenger seat will be shaking like a mofo too? hehe, kinda wierd. Anyway, took my car in and had the rear tires re-balanced (I had just bought new tires but apparently they wheren't balanced very well) and the problem is almost completely gone. I can BARELY notice a slight hint of a vibration now, but I'm just being picky. No vibration like it used to, and my wheels are static balanced.
