The OpenBeacon project is an open source hardware and software active RFID device. OpenBeacon tags consist of 2.4GHz transceivers and a PIC16F684. One use of the project was to create CCC Sputnik to show the downsides to information culled using data mining from large tracking systems. People who chose to participate and wear the Sputnik tags did so voluntarily to create a database of material for further study. The hardware schematics (PDF) for the first version tags as well as the firmware for all versions has been released. Further creative uses of the OpenBeacon project are strongly encouraged.
As a reminder, the 24C3, the 24th Chaos Communication Congress, call for participation ends on October 12th. The theme this year encompasses all hardware projects and more specifically, steampunk themed submissions. Check out the CCC events blog for more information.