Sputnik
The 23rd Chaos Communication Congress (23C3) is a four-day conference, lots of tech and hackery, check out the badges attendees are wearing–

“CCC-Sputnik is the first public appearance of the Open Source Project OpenBeacon.org and every attendant of the 23C3 is warmly invited to take part in this realtime in-building location tracking system. The CCC-Sputnik project intends to demonstrate the actual possibilities and threats of tracking and data mining with the RFID technology.

The transmitting device is a small 36x36mm pcb, powered by a coin cell. A Nordic RF Chip and a PIC microcontroller are used to control the 2.4GHz RF communication and a red LED indicates the transmitting periods. The device also provides a touch sensor in the upper right corner for further interaction possibilities.

There will be 1000 Sputnik devices available for the expected 3000 guests at the conference. Each device will transmit its unique id. The transmitted signals will be collected by up to 25 RFID base stations within the congress building and transferred to a centralized server via Ethernet. “Link.