If I run the python console and do

import matplotlib
matplotlib.__version__
import matplotlib.gridspec as gs

I see that the matplotlib version is 1.2.1.

If I do help(gs) I see the Gridspec class.

However the following code

import matplotlib
import matplotlib.gridspec as gs
g = gs.Gridspec(1,1)

produces the error:

AttributeError: 'module' object has no attribute 'Gridspec'

Why can't I create a new Gridspec object?

You meant to type g = gs.GridSpec(1,1). The "s" in "Spec" is capitalized.