You know when you're in line at the supermarket, with about 4-5 people in front of you. Then a new line opens up and the cashier yells, "I'll take who's next in line." The people in front of you rush to the new line, leaving you with a cashier who's all yours.
That's why I'm sticking with AT&T. The Verizon line will open up, everyone will rush over, and then leave me as the only AT&T customer on its network. Imagine how fast my 3G will be!