How does the Verizon iPhone 4 data plan work?

In order to access internet and other features on the iPhone without wifi, what are the additional charges? I currently have an iPod touch, and the internet is free as long as I am in a wifi zone. Is it similar with the iPhone? Thanks.|||You would purchase a data plan from Verizon. Since iPhone 4 is considered a smartphone, it requires a data plan. Verizon has unlimited data for $40 a month. Or Verizon has other data plans for a lower cost per month.