Tubeless tire conversion product

Has anyone seen these tubeless tire conversion things, that look like a bicycle inner tube inside of a split rubber hose? I just went down to Iron Pony yesterday and spotted this product. I think they were like 90 bucks, and they had one for each wheel diameter.

The concept of the thing is that the rubber hose, holds the bicycle inner tube against the wheel, and the small tube seals against the rim over the spokes. This allows you to run a tubeless tire on a spoke wheel. There are two valve stems, one for the tiny inner tube, and one to inflate the tire. I suppose you have to drill a hole in your wheel to accomodate the second stem.

Looks feasible enough that it might work. Anybody using one already? I'm pretty satisfied running a tube in my car tire, but might give this thing a shot (if my car tire ever wears out).

I wonder how it holds with the centrifugal forces at 90? Hmmm...