This might be a contrary view, but Cython has been ready for production for quite a while while PyPy has still been getting its boots on: http://cython.org/ It actually works right out of the box. You can download it and get real world examples to work in five minutes. It works with C++. It works with numpy. http://wiki.cython.org/WrappingCPlusPlus http://wiki.cython.org/tutorials/numpy It's the real deal: ridiculous…
Seriously, pypy outperforms Cython in pretty much all cases unless you provide type informations and even then, pypy is often faster. Complex projects, like twisted or django tend to have a flat performance profile - in order to run them reasonably fast, you would need to put types everywhere and very likely convert classes to C structs. This is not going to fly and you know it, cython is only useful for people inside numeric community.
Also, it's true that pypy took many years to build, but it actually does work. If you claim that pypy never shipped, it very likely means none of the "new python interpreter" projects would ever ship for you, but hey, there are people out there for whom it works.
Cheers, fijal