For one thing I'd be interested to see if Python runs any faster when it's hosted in Common Lisp, since it will presumably reap the benefits of a native compiler that produces machine-code instead of byte-code.
This is essentially what the PyPy (Python-in-Python) effort is betting on, except that by building the system in restricted Python, they're also hoping the system can also optimize itself to higher levels of performance. It will be interesting to see how the results of Python-on-Python compare to Python-on-Lisp.
