I was having problems on my new 15" macbookpro with the Verizon express card funking out when I closed the lid. Here is their response:
I apologize for any inconvenience you have encountered as a result of your laptop going to sleep, and causing any difficulties with accessing the Internet. Please know that the VZAccess Manager connection utility must be closed, and connections devices ejected/disconnected, before a laptop (Mac or PC) is put into sleep/hibernate mode. Stable operation is not guaranteed if the utility is open when a laptop is put into sleep/hibernate mode while connected. To be on the safe side, VZAccess Manager should be closed and the connecting device removed from the laptop before putting the laptop into sleep/hibernate mode.
Please note that by default many laptops go into sleep mode when the lid is closed.