"use" means you bring SOME manifestation of the patentable innovation to bear. you have to be able to point at an implementation. that means 99% of the patent trolls will bugger off because none of them wants to do any real work anyway, and more to the point, they would have no idea how.
there's nothing saying you even have to have intentions of using, marketing or giving away the implementation...but you have to demonstrate that you are actually have the capacity to create an innovation, not just churn out whitepapers to tax others who actually will implement.