Wearable devices are finally transitioning from hype to mainstream, aided by integration of valuable transducers, identification of application and use cases, ramp up of cloud services, and increased public awareness and interest due to Apple's watch introduction. Although still a nascent field, several themes are emerging that this talk will explore. The first is the evolution of capability from performing simple functions such as step count, to becoming contextually aware products. The second theme is the implications of targeting far more than just the wrist for the wearable device's residence. The third arises from the desire for "always on" capability, small size limit, and appeal of charging only every few days. In consequence, power is one of the most important parameters impacting the entire system design.