Researchers at UC Irvine have designed the first radio using nano-sized parts. Why? Even they didn't have a convincing answer in this interview. Not all the parts in this AM radio are tiny; so far only the demodulator is made out of a carbon nanotube that's 50 microns long. But it's the first step in making a functioning radio so small that it's invisible to the naked eye.
The department of defense is funding the research. We're not exactly sure why the army would need an invisible radio, but we have a feeling Steve Jobs would show interest. Maybe he could tuck one into the next iPod Nano, bringing some authenticity to the gadget's name. Here's a video demonstration of the radio in action.