I know there is some support for running Mathematica from Python, but is there any way to do the reverse. For example, to import some Python classes and use them in Mathematica?
If all you want is to invoke Python scripts and use the output they generate in Mathematica, then simply
There's a "Python link" called Pythonika. I have used it briefly and it works.
What it does:
It does not provide any means to work with classes directly. Also, the implementation is rather hackish using unsafe practices (e.g. symbols are not localized to a context, and this has bitten me). To implement a link properly it would take lot more work.
I made a few basic fixes (e.g. using contexts), but I haven't used the thing in a long time. Contact me if you want the fixes.