Researchers at UC Berkeley working on Pico Radio hope to have low cost, low power nodes the size of a shirt button. They see these as remote sensors. Very interesting.

PicoRadio Charter:
Develop meso-scale low cost (< 50 cents) transceivers for ubiquitous wireless data acquisition that minimizes power/energy dissipation.
>> Minimize energy (<5nJ/(correct) bit) for energy-limited source
>> Minimize power (<100uW) for power limited source enabling energy scavenging

By using the following strategies:
>> self-configuring networks
>> fluid trade-off between communication and computation
>> Integrated SOC approach, aggressive low-energy architectures and circuits