[icebraining]

There's a recent blog post[1] by one of the CPython core devs. He talks about Pypy, not Jython, but I think it applies too:

Personally, I think the status quo in this space is in a pretty good place, with python-dev and CPython handling the evolution of the language specification itself, as well as providing an implementation that will work reasonably well on almost any platform with a C compiler (and preferably some level of POSIX compliance), while the PyPy crew focus on providing a fast, customisable implementation for the major platforms without getting distracted by arguments about possible new language features.

[1]: http://www.boredomandlaziness.org/2011/08/of-python-and-road...