Tinycopter is a 13″ tip-to-tip quadrotor whose most recent version was built a few weeks ago. It has all of the same component types which will also appear in Chibicopter, namely a 6 DOF inertial sensor, four miniature R/C aircraft ESCs, a 2-cell lithium polymer battery, four miniature R/C motors, and 5″ propellers. The stabilization algorithm is Arduino-based.
Tinycopter uses a standard R/C aircraft radio, not an XBee.
While Tinycopter uses an analog Sparkfun IMU (http://www.sparkfun.com/products/10010) which has been discontinued, Chibicopter will use a Pololu miniIMU (http://www.pololu.com/catalog/product/1265) which communicates through I2C. Arduino has hardware I2C support, so the transition will not be difficult. The digital IMU also has useful features such as auto-zeroing and auto-offset.
Tinycopter uses discrete packaged 6 amp motor controllers, while Chibicopter will use the smalest discrete controllers sold on Hobbyking, which is a bare PCB, and mount the PCB on the motherboard on headers.
Tinycopter’s full build report history: http://www.etotheipiplusone.net/?cat=87