go here
http://www.hotrocker.com/

It has nothing to do with the cam, but instead the rocker-arm ratio which is being changed. Basically a the rocker arm is hollow with an adjustable pedistol in the middle that changes positions during a certian RPM adjusting the the lift of the rocker arm. They make them for Chevy V-6's and 350's as well. I am sure it is not the best VVA, but it is a good simple solution for push-rod engines that can be added to virtually any pushrod. And it does effect lift, which only Ferraris and Honda's do. They actually used a similar VVA in some WWII aircraft engines.