I organized a VM panel at PyCon this year where a representative from each of the major VMs (CPython, Jython, IronPython, and PyPy) will be in one room to answer your various questions. To help get questions from people who cannot attend along with making our esteem MC's job easier, Jacob (who is the moderator) and I have set up a Google Moderator page for the panel to propose qauestions.
Please propose questions or vote questions up and down so that Jacob can come with a battery of questions for the panel to fill in lulls during the Q&A. And I think all talks are being recorded this year so the panel should eventually end up online.
Oh, and if you are not attending PyCon, you still have a chance to register and come!