Asynchronous I/O for the Python subprocess module has been successfully implemented in both the Python 2k and Python3k branches. Building off of that functionality, I also implemented a wrapper class for the asynchronous I/O so that child processes could act as stand-ins for file objects. The unit tests I produced for the asynchronous I/O and file-like object run flawlessly.
In the last half of Google Summer of Code, I will be be perfecting my file-like object for subprocess.Popen, porting Mark Hammond's win32 modules to C and integrating them with the _subprocess.c file as the asynchronous I/O depends on his code to run. When all is said and done, I will produce a PEP for my changes and attempt to get them integrating into future Python releases.