...or you can read this very short description.
In a telemark turn there is a trailing ski and a lead ski. The trailing ski is the one where the skier's boot heel is off the ski. When this happens, the sweet spot of the edge should accomodate a position further forward toward the shovel because you're now using the point under the ball of foot to pressure the ski instead of the point under the shaft of the tibia. Scotty Bob's tail design effectively moves the sweet spot under the edge for the trailing ski for better trailing ski carving. The web site has a very good explanation if you care to read more.
So, you see there's a clever ingenuity with this design. Scottybob has a very successful carving ski that has been in production for a few years with growing popularity due to the proven function of the design.