Gamber-Johnson have been making vehicle notebook mounts for years. I've used one in the past with a Panasonic Toughbook and it worked quite well. It even had a mount for a small printer underneath. I believe the LAPD uses a similar setup in their cruisers.
To be honest, the car he used is more of a bottleneck for this project. On my car I replaced the factory headunit with a double-DIN JVC with BT and NAV. Now I can use my phone without a second BT gadget, and not worry about keeping it charged either. A simple $20 12V adapter keeps my 3G smartphone charged, and I can tether my phone too, making the MiFi device totally unnecessary. My data plan doesn't subject me to a 5GB cap either. As for notebook power, I carry a second charged battery, giving me all-day power, be it in the car or on-site with a client. Much less gadgets, much simple to hook up, and much less to carry. Never mind leaving nothing in the vehicle for thieves to break in and knock off.
His set up is definitely not typical, but it's important to remember to go with what works best. This may work well for him, but it is not something another road-warrior may consider functional for their need or efficient for their budget. There are better ways to do what this guy did here.