A bit more info:
I used the Pantech 4G modem in both Nashville and St. Louis, where 4G service is currently available. It will use a 3G signal if 4G isn't available. I was able to use it as we drove along the interstate between St. Louis and Kansas City. Verizon wireless offers 4G in approximately 2 dozen cities currently, and will provide nation-wide coverage by 2013.
If you travel frequently, taking your own internet along allows you to work in places you couldn't before- like in the car- and is very helpful in places where wifi is an extra charge (airports, some hotels).
What I liked about the Pantech modem was the rotating USB connector and the (included) optional extension. It was very handy both for space on my netbook and for optimal positioning of the device to receive a signal, if necessary.
The Pantech UML290 4G modem is $99.99 with a 2 year Verizon wireless contract. The monthly fee (4g plan) is additional; a 5GB plan is $50 and a 10GB plan is $80.
For more information visit Verizon Wireless.
Disclosure: I was given the Pantech 4G USB modem to use on a business trip. I have been a Verizon Wireless customer for over 5 years; they have earned my loyalty due to their large network and helpful customer service. I was not paid for this review; all thoughts are my own.