The traditional chessboard is not very accurate due to the corner concept, the motion blur from camera, etc. This new pattern was designed to combine the detection speed from rectangle with accuracy from circle fitting. And this detector could be easily integrated into OpenCV's calibration module.
The default pattern is showed below, and you could use the Qt tool in the tool/ folder to generate a new pattern image with a different size.
If you use SCons as your build tool, and have opencv installed, then simply type this to build:
scons