Rhino uses IronPython 2.7.5 (the .NET version of Python). There are some plugins that let you interface with CPython (I believe 3 should be possible here).
Edit: To be completely explicit, I am referring to these:
Rhino uses IronPython 2.7.5 (the .NET version of Python). There are some plugins that let you interface with CPython (I believe 3 should be possible here).
Edit: To be completely explicit, I am referring to these: