How much does an iPhone 4 (Verizon) cost monthly?

Verizon is now selling the iPhone for free along with a two-year contract. Obviously the free part is what has grabbed my attention, but how much is it going to cost me monthly to own one?

Its going to cost about 100$ a month now that Verizon is using the share everything plans. You get unlimited text, calling and 2gb of data.