Verizon is locking its own customers out of upgrades. From Gizmodo:
Here's something for our hefty "WTF, Verizon?" file: The BlackBerry Tour, soon to be Verizon's top phone, cannot be pre-ordered by existing customers under contract who want to upgrade. What's worse, upgrades may be blocked even after the phone's release.
Cellphone subsidies exist to create a consumer relationship that resembles debt. The question "Why would Verizon stop people buying phones?" yields the answer "Because selling phones is like selling credit." They make a lot more money, but have to be careful about who they do business with: existing debtors are low on the pole because they've already got you.
This is why customer service at the carriers so notoriously ends when you sign up. The only real obligation past that point is that you have to give them money for two years.
Update: Verizon changed its mind. Yay!