Hi All !
I am Oliver from Dresden Germany. Received my BrickPi yesterday from Generation Robots in France. I had no success with normal 9 Volt Batteries.
But now i have two solutions for stationary and wireless operations.
Please see here for some details and photos.
http://dl6kbg.blogspot.de/2013/10/brickpi-power-solutions.html
I tested all with LED.py and LEGO-Motor-Test.py.
Works great.
Have Fun !
Oliver