Cython participates in the GSoC 2011 under the umbrella of the Python Software Foundation.
Any of the ideas at http://wiki.cython.org/enhancements could make a good project, though they vary greatly in scope and completeness, so it'd be advisable to contact us first.
The goal is to rewrite modules in CPython's standard library in Cython, both those that are currently written in C and those that are written in Python. The intention is to
- simplify the implementation to make it easier for CPython core developers to maintain their code base and
- try to make the modules even faster than they are to show off Cython's optimisation capabilities
in that order.
A related task could be to take existing Python modules in the stdlib, to profile them, and to add external type annotations to optimise them when being compiled with Cython.
The nice thing about this project is that you don't have to be an expert of CPython's C-API, nor a core developer of Cython. However, you will have to program efficiently in Cython, and write fast code in it. Writing Cython code that is easy to read and maintain, and at the same time fast enough to replace the existing manually tuned C code is the challenging bit here.
Both the task of showing Cython's ability to efficiently (and compatibly) implement or compile parts of the stdlib, and the resulting testing of Cython (and bug reporting/fixing) against real world Python code would be very valuable to our project.
Suitable first candidate modules are all accelerators, e.g. "functools" or "itertools", as well as simple/low-level modules like the "math" module.