It's exploratory in the sense that we are seeing if this general approach works for CPython. But if this exploratory work shows promise, then we will see it through. And since I'm also a member of the Python development team I always want to see Python be faster and succeed more. :)
Pyston seems to be catching up to PyPy fairly quickly ...not sure if there is anything transferable to pyjion, but if you haven't done so might be worth checking out.
Also for getting around the GIL, PyParallel seems to have a really interesting (and seemingly successful approach: http://pyparallel.org/
Its being worked on by one of the Guy's at continuum...and It's definitely in continuum's best interest to help python's future so I'm sure they wouldn't mind collab.
Once we're back into Python, though, Pyjion's JIT'd version of whatever would kick in and do its thing. Perfect combo.
We are also aware of Pyston. There might be a chance that they could end up using our JIT hooks, but they also started a full year before us so they are not currently structured to plug into CPython like we're trying to through the API we're designing (although hopefully they will be able to, but who knows).