Wasting no time on their Falcon rocket program which is already transporting equipment back and forth to the ISS, SpaceX has already gotten an upgraded version of the engine powering said rocket in production.
The new Merlin 1D engine has been approved after going through a rigorous testing program (video of some of which can be seen below). The new engine will be installed on the Falcon series of rockets beginning this summer. Achievements for this rocket include the highest thrust (measured at 147,000 lbs) to weight ratio of any liquid fuel rocket in history and a 50% decrease in parts and cost. This is also the rocket that will be used on the Grasshopper program as well. Love what SpaceX is doing and accomplishing...Love it!