Yes, I see this as a way to create a complete system that collects methane from it's landfills, then uses some of that methane to collect more trash, then use some of the excess energy for other municipal vehicles, heating homes, generating electricity or cooking fuel.
I'm sensing a disconnect here. NYC can collect methane from its existing (but closed) landfills. Do they generate enough to fuel the trucks? "New" garbage is shipped out of state or burned for energy. How is NYC going to get the gas generated from the out-of-state landfills back into the city to fuel the trash trucks? I suppose the transfer trucks (those large, over-the-road trucks traveling between NYC and the landfills) could be fueled at the landfills, but not the NYC trash trucks. Also, even if you fueled the transfer trucks, you'd run into the CNG range-limitation of 100 miles or so (which could be overcome by LNG, but that's another thread).