The code is released under the GNU General Public License.
This is the code for the Android app to control the Balancing robot.
The source code for the robot can be found here: https://github.com/TKJElectronics/BalancingRobotArduino.
Also check out the video: http://www.youtube.com/watch?v=N28C_JqVhGU.
For more information see my blog post at http://blog.tkjelectronics.dk/2012/03/the-balancing-robot/ or send me an email at kristianl@tkjelectronics.dk.