Verizon, like AT&T has now started blocking jailbroken phones from using un-sanctioned tethering apps. Verizon will now require users to be subscribed to a mobile tethering plan to be able to use tethering at all.
Users on the Verizon network who try to circumvent the paid subscription plan will be redirected to a page to purchase the upgrade. The plan which will cost an additional $20 a month.
Honestly I think that the carriers are blocking these services because their networks are getting too saturated and it is costing them too much to add new hardware. Verizon is the number 1 mobile network followed closely by AT&T whom will overtake Verizon after the merger completes. These companies honestly need to start lowering their data prices otherwise Sprint or other companies, with unlimited plans will start to take some of their users.