Some reading material for you:
BroadbandAccess Terms & Conditions Specifically, this part:
"If usage exceeds 5 GB per line during any billing period, we reserve the right to reduce throughput speeds of any application that would otherwise exceed such speed to a maximum of approximately 200 Kbps. These speeds are subject to change, in our reasonable discretion, in order to address network issues. "
Verizon Wireless: When we say "unlimited data," we mean 5GB worth of "unlimited data"
Verizon Admits 5GB Wireless Broadband Cap - Still advertises unlimited -- Verizon exec comments on our report... - dslreports.com
Verizon Wireless raises PDA data / voice bundle prices - Engadget Mobile