About as useful as a bullfrog on Paris Hilton's mamms...
...at least in Los Estados Unidos, where it would not be allowed through security...and the short walk from the taxi stand to the curb-side check-in isn't worth the hassle. Especially since there are still Red Caps to be had for US$2 per bag.
On the other hand, if they were £96 instead of £965, I'd get a half-dozen and have them ALL following me through the aeropuerto just for the giggles it would cause. Take a circuit around the check-in desks, banging folks feet and causing general mayhem. Well worth £300 just for the You-Tube opportunity...
@ Seat: in most US airports, the guys with the golf carts will pick up ANYONE that flags them down, and for a tenner, give you a ride to your gate. This is VERY key knowledge in places like Phoenix (PHX) or St. Louis (STL) where connecting flights may be as much as 1.5 MILES (3KM) apart (yeah, I measured it), all within ONE terminal. Now, FINDING the golf-cart guys is a challenge, but I use 'em all the time - when they're there.