As mobile systems become increasing prevalent, they are being called upon to run multimedia applications traditionally associated with the wired domain. Unfortunately, battery capacity is not keeping pace with system demand, driving the demand for energy efficiency. Unfortunately, the encapsulation of traditional layered designs limits the energy that can be saved because layers cannot cooperate. However, monolithic systems have been shown to be inefficient and unscalable. In this paper, we present the design and implementation of a system consisting of multiple adaptive applications, and adaptive MAC and transport layers. We evaluate this system by implementing an adaptive video encoding application, showing that a layered approach sharing enough information can enable energy efficiency while maintaining sufficient isolation to allow the replacement of components without requiring a whole-system redesign.