The Trove project has a policy of trying to write as much of its code as possible in the form of well-documented enhancements to the Python standard environment. Here are the things the Trove project has fed back to Guido Van Rossum so far:
New features, and documentation patches, for the standard rfc822.py module which support more general processing of header spans consisting of defined sets of legal headers (this is used in the TRL parser).
New features and complete documentation for the standard multifile.py module. The new features make it more flexible and extensible. (It's used by the TRL parser.)
New features and complete documentation for the standard cmd.py module. The new features make it more flexible and extensible. (They're used, among other places, in the test harness for Trove's archive.py module.)
New features, a test harness, and complete documentation for the standard smtplib.py module. The new features include support for ESMTP and issuing SMTP VRFY commands. The trovesend tool requires smtplib, though it doesn't require the new features; I put them in while grokking the existing code.
I will probably produce a documented semaphores- and shared-memory module before I'm done, in order to synchronize instances of the shovel. This module may incorporate Vladimir Marangozov's well-designed but undocumented semaphore module, depending on how license negotiations go with INRIA.