I just received my Phantom 2 quadcopter with H3-2D gimbal, and was pleased to see that DJI has incorporated “anti-drop” screws into their vibration mount. You no longer have to worry about the entire gimbal and camera assembly coming completely off of the quadcopter.

Update: Steve Doll informs me that other gimbal designs solve this by compressing the balls (as they were designed to be used) instead of pulling on them. For example, this Tarot gimbal mounts the camera to the top plate, which compresses against the bottom plate, which is attached to the quad.