We now (3.3) have a shlex.quote function. It’s none other that pipes.quote moved and documented (code using pipes.quote will still work). See http://bugs.python.org/issue9723 for the whole discussion.
subprocess.list2cmdline is a private function that should not be used. It could however be moved to shlex and made officially public. See also http://bugs.python.org/issue1724822.