If you have long hair and are seeing greater than normal dropped calls on Verizon, this might be reason for it. See the post from "Pamela". Verizon/Moto should really fix this problem if they don't want people blaming Verizon's network for a problem that lies elsewhere.
Dropped Calls? - Android Forums
In short, the proximity sensor on the Droid does not work well if you have hair between the phone and your ear. While you are in a call with the phone held to your ear, the sensor accidentally activates the screen.
The hair interferes with the sensors detection that your face is still near. Your cheek ends up hitting the end key or the mute button while you are in the call and you think that the call dropped.
My wife sees this issue on almost every call but it works fine for me. We got the phone replaced and she sees the same problem on the second droid as well.
This is a very frustrating problem that they need to fix soon. I think the droid is meant to be a phone first and camera, browser, etc, second. While all the additonal features are cool, I can't justify spending so much on it if it can't do calls well.