I just noticed that my IPython (as called by run-python against my variable python-shell-interpreter) doesn't see all my environment variables, but IPython called from bash in the terminal does. I exporting MYVAR in both .bash_profile and .bashrc.
When I evaluate os.getenv('MYVAR') in the terminal ipython, it works. But inside of emacs nothing shows up. Why would it be different in Emacs?