Since the 2007 Titan has this technology I thought it would be nice if we understood it.

Valves control the flow of air and fuel, into the cylinders and exhaust out of them. When and how long the valves open (timing) and how much the valves move (lift) both affect engine efficiency.

Optimum timing and lift settings are different for high and low engine speeds. Traditional designs, however, use fixed timing and lift settings, which are a compromise between the optimum for high and low speeds. VVT&L systems automatically alter timing and lift to the optimum settings for the engine speed.

Potential Efficiency Improvement of this is 5%.

By the way, General Motors patented the first variable valve timing and lift or smart valve system in September of 1975.

This link will take you to a hardcore PDF on this.