[jey]

No, PyPy is a full Python implementation that uses program analysis to identify and JIT the JITable parts of the code.

The FAQ says that PyPy is a drop-in replacement for CPython unless you depend on a CPython extension module. http://codespeak.net/pypy/dist/pypy/doc/faq.html#is-pypy-a-d...

[jd]

The drop in replacement is slower than CPython. Likely to change in the future, but still.