Matplotlib 1.1.1 cannot be directly installed via the installer in the dmg image provided in sourceforge, at lease in my case.
I decided to build from source code.
Several libraries are missing in my Mountain Lion.
/usr/local/include/ft2build.h:56:10: fatal error: ‘freetype/config/ftheader.h’ file not found
after install freetype, a soft link should be made for matplotlib to locate the freetype.
ln -s /usr/local/include/freetype2/freetype/ /usr/include/freetype
You can test the matplotlib by importing the pylab module in your python shell.
from pylab import *