I, too, came from a BB device. I had a Curve. It makes sense that there are many BB users switching. Usually you will get a lot of customers with the same carrier buying a new phone. Before the Droid, it seems that the BBs were the best smartphones that Verizon had to offer. Hence, the many BB users switching to the newest, best smartphone in the Verizon arsenal.
I was debating switching to AT&T for the iPhone, but I heard rumors that iPhone was coming to Verizon in 2010. I really didn't want to leave the Verizon network, so I decided to wait. I was very close to getting a Tour or a Storm2, but then I heard about the Droid coming. After reading about it, I was hooked and knew that would be the phone for me - no need waiting for a possible Verizon iPhone with the Droid being released.