I missed the talk about this subject at the last MDRA meeting. Today I found an article on Centauri Dreams - A Swarm of Probes to the Stars. The article also provides a link to the related IEEE Spectrum article, which was written by Dr. Mason Peck...who also spoke at MDRA!
Cornell researchers have hand built Sprite prototypes, which have been mounted on the ISS's MISSE-8 (Materials on International Space Station Experiment 8) pallet. This experiment will assess how the integral solar-charged capacitors will perform and more importantly, whether their RF 'pings' can be detected on the ground. The Sprite's radios employ ultra-low-power 902-megahertz radios whose signal is a mere 7 percent of the background noise. To overcome this deficit, the radios use CDMA coding. CDMA, which is used in GPS and cell phones, can allow you to pull weak correlated signals from strong background noise. [thinkingoutloud] I didn't see this in the article, but it can also be used to sum sets of weaker signals into a stronger one. Globalstar does this. I don't know if this would have any applicability to a swarm of Sprites. [/thinkingoutloud]
The Sprites would be deployed in large swarms but with size, and hence power, limitations, it is not envisioned that they will intercommunicate with one another. They would be small and light enough to make use of the solar wind and to ride the magnetic fields. Pretty wild stuff.