The idea of desmodromic valve gear is simple - the poppet valve is mechanically closed, as well as mechanically opened.  The engine can be revved like crazy when it gets raced. This is difficult to make under conditions of mass-production, though.  Ducati motorcycles have probably the only production engines available to normal customers with this system.

A more contemporary take on this idea has recently arrived in Formula One racing with the pneumatically-operated poppet valve. This system eliminates the cam mechanism completely and uses a double-acting pneumatic solenoid and computer to provide variable valve timing, opening duration, lift and opening/closure rates.  Fantastic performance is available, however the system is a thing of horror to backyard mechanics.