Weeehooo! Looks like something FUN to try during our LONG winters in Wisconsin!! I think I'd opt for a nice sled instead of skiis though!
My mom used to do skijoring when I was little. I thought it was so... cool, and I still do. She gave it up when my brother and I were little, and a few years later her big horse died, but maybe someday I can convince her to do it again with me.
Have done this with dogs on skis and roller blades, this looks like another fun way to try. another good reason to view this site.
It looks like something that was just bound to happen when humans first domesicated the horse. But it looks like fun.