I've been using a Kyocera KR2 router on board for the last two years. I plug in my Verizon Aircard to it, and also my mast mounted wireless amplifier, and I can pick and choose either EVDO network services or WiFi. There are other products on the market too, such as ones by Cradlepoint. Check out
http://www.evdoinfo.com for a lot of information on this technology. I'd probably lean away from the MiFi due to a lot of restrictions and other devices on the market that don't have those same restrictions...