@chomps - I do not own one personally nor have I tried one but I have a friend who lives out west who has ridden them and he's told me about them...
Apparently there is a very steep learning curve with freebord's. It's a matter of gauging the pressure with the third wheel, which is essentially mounted to a device similar to that of a wheel on a shopping cart. It oscillates as you turn.
Obviously these things are for downhill only - it would be difficult to push one of these things with the binding clip things permanently attached to the deck.
I was all about these things for awhile but never bit the bullet - didn't have the cash nor am I in an area conducive to that type of activity. I feel like you would need a long, open, minimally trafficked stretch of road to really get the most out of these things.