The owner of this iPad is very daring. He decided to break open an Apple iPad 3G, remove the 3G/GPS components and some how fit a Verizon MiFi device inside, powered by the iPad.
With a bit of soldering, some pliers and some imagination the project came together very well and now allows the iPad to be used as a WiFi hotspot and allows the iPad to connect to that WiFi hotspot which uses the Verizon network.
The microSIM slot was not needed after this modification so instead of just leaving the blank plate there, a switch was cut down to size allowing the MiFi to be switched off when not needed to save battery life.
It's an impressive hack and one I think requires a lot of skill to achieve. If you want to try this yourself, check out the full instructions here that go in to step by step detail on how it was put together.
Just remember that as soon as your iPad is carefully opened up that you have indeed, lost any warranty. Proceed with caution and good luck!
Also check out the images on the dish site that show what kind of speed improvements Verizon has over the AT&T network in the area where it was tested.