import Blender

ob = Blender.Object.Get('Whatever')

wx = abs(ob.getBoundBox()[6][0]-ob.getBoundBox()[0][0])/2.0
wy = abs(ob.getBoundBox()[6][1]-ob.getBoundBox()[0][1])/2.0
wz = abs(ob.getBoundBox()[6][2]-ob.getBoundBox()[0][2])/2.0