I did this project for real back in the day, called Rupy[1] which would run the Python VM in the Ruby VM. It was was a fork of RubyPython, which demonstrated the concept.
Eventually the main developer resumed development and I merged all my code in his repo, which is still active[2].
That's Python running inside Ruby, while the OP was (ostensibly) Ruby inside Python.
Rython [1] purports to run Ruby inside Python, although it hasn't been updated since 2009. Unlike RubyPython it doesn't actually embed a VM. Instead, it looks like it starts up an XML-RPC server on the Ruby side and the Python side acts as a client.
Eventually the main developer resumed development and I merged all my code in his repo, which is still active[2].
Check it out it works pretty well.
[1] https://github.com/steeve/rupy
[2] https://bitbucket.org/raineszm/rubypython