Ceri's bought one, but rather than try and explain myself, I'll quote from the manufacturers website!

"Just twist and go! The RipStikŪ Caster Board brings the carving thrill of surfing and snowboarding to dry land! It's unique twisting motion moves you forward with out ever pushing off the ground! The RipStikŪ's 360 degree inclined casters and pivoting deck provide a unique carving motion. A concave deck and traction plates provide increased foot control. The RipStikŪ Caster Board comes equipped with 76mm urethene wheels and high performance bearings for an unbelieveably smooth ride. All you do is twist and go! The RipStikŪ Caster Board, like nothing you've ever ridden!"

Here are a collection of Ceri trying out his new gadget!