Setting axes position is similar in Matplotlib. You can use the get_position and set_position methods of the axes.
import matplotlib.pyplot as plt
ax = plt.subplot(111)
pos1 = ax.get_position() # get the original position
pos2 = [pos1.x0 + 0.3, pos1.y0 + 0.3, pos1.width / 2.0, pos1.height / 2.0]
ax.set_position(pos2) # set a new position
You might also want to take a look at GridSpec if you haven't already.