Builtin JIT or similar?

[Afanasiy]

Are there any plans to improve the performance of standard
Python (in some cases) through the use of a JIT or similar?

I have discovered Psyco, and it is very interesting, but can break some
code, does not come with Python, and requires small code modifications.

What I mean is something which does not change the behaviour of a Python
application, and may not even require any modification of the code.

Perhaps it could be turned off with a commandline option.