I saw this video a few days ago on eBaum's World, one of those sites where you can watch people doing funny or insane things on video... at the time I thought to myself: "Hmmm... looks like those two guys might have been seriously hurt at the end of this little video!" and I was right.
According to this article, one of the men in the zorb (that's the name for this inflatable gerbil ball for humans) died of severe spinal injuries and the other was still hospitalized with his injuries after both were ejected from the zorb when it plunged into a gorge off of the side of the ski slope.
I've got a DVD of a Peter Gabriel concert in which he climbs into one of these and "zorb" surfs across the top of his audience. That looked like a lot of fun.